It's not in the accusative case. Although, for those words, the accusative would look the same. The accusative ending is "ı, i, u, ü" (depending on the vowel harmony) and if the word ends in a vowel, you insert an additional "y", so it's easier to pronounce. But since the words Yemek and Zaman don't end in a vowel, it's not the case here, so the accusative forms would be: Yemeği and Zamanı, indeed. Now, the possessive 3rd person suffix is also "ı, i, u, ü"; however, if the word ends in a vowel, this time we add an "s" as a helper. So for the words Yemek and Zaman, you get "Yemeği" and "Zamanı", but if the word was something like "pencere" (window), for instance, you would get "Penceresi" for the possessive, while its accusative form would be "Pencereyi". I'm not sure how much sense I've just made. If I've confused you further, let me know.
Unrelated to the original question but related to your very comprehensive answer: "ı, i, u, ü" For the possessive 3rd pers, if the word ends in a vowel we add "s" as buffer; For the accusative, if the word ends in a vowel we use "y" as buffer. If the accusative comes after an already added suffix, the buffer consonant is "n". Is this correct?
I am wonder is this just a frase, without real sentance? Which word have accusative sufix, and which one have possesive? And how would you translate this... why not like - evening is a dinner time? Akşam, in this case significate smtg else, like it is evening so it is dinner... will sabah yemegi zamani mean it is breakfast time :-D :-D
It is breakfast time: Kahvaltı zamanı.
It is dinner time: Akşam yemeği zamanı.
Evening is the dinner time: akşam, akşam yemeği zamanıdır.
Nothing in 'Akşam yemeği zamanı.' has accusative case. 'Yemeği' has a possesive suffix. And yes, it is more like a phrase or incomplete sentence (Şimdi akşam yemeği zamanı. - It is time for dinner at the moment.)
You would use "o" to refer to something specific. If you used "o" in this sentence, it would mean something like "THAT ONE is dinner time" or something. The "it" in the English sentence is called a dummy pronoun. It doesn't refer to anything specific, it just the plays the role of the subject in the sentence, because English requires that we use a subject at all times. Turkish, on the other hand, is in fancy terms a pro-drop language, which means the subject can be omitted. Because there are specific endings for each person (I, you, we, they etc), the subject of a sentence can be hidden if it's obvious in the context.
Also, Turkish doesn't use "is" very often. It's -dır. So you could technically say "Akşam yemeği zamanıdır", but please don't. It's no longer used in such simple sentences. (We have a guide on the suffix -dır [https://www.duolingo.com/comment/8649151] in the grammar portal, so you can check that out some time.)
So that leaves us with a sentence that doesn't need a subject and that has "is" as its verb, which we just don't use. So a noun phrase, let's call it "XYZ", with a full stop at the end can be interpreted as "it is XYZ".
So, to clarify, is "akşam yemeği zamanı" a noun compound nested inside a noun compound? I.e., there is no possessor/possessed genitive structure here, right?
After reading the comments, the only way I can see how this can make sense is if I parse it like this:
[[akşam yemeği] zamanı]