"It's clear that this pair of pants suits you very well."
Translation:C'est clair que ce pantalon te va très bien.
This would be a good question for an actual French speaker because as I have learned it "-ci" could be used here, but Johnny is correct in saying that "-ci" and "-la" are usually used together. This one or that one. But as far as I understand, it could be used here. Especially if the listener is right there with you.
The vous OR te is the indirect object pronoun of the verb go... the idiom is 'goes well to you' "ca te va" this goes well (to/by/on... best literal english translations== suits you) YOU. The subject of the verb 'aller(conjugated va in this sentence) is the noun 'pair'(of pants)(pantalon) '...singular in french. So while 'vous' would be right for formality... the verb aller would still be conjugated 'va' because what goes well.. is the singular noun 'pair' (of pants.
Here is a nice link for clothes phrases in french. https://www.youtube.com/watch?v=85Vvjqr8-h8
It is a sort of idiom with the verb 'aller' used reflexively. Essentially when we say "it suits you" in ENGLISH, the french translates it to "IT goes to you'.. SO "CA for it/te (the relexive pronoun)/VA the 3rd person present of the verb ALLER. So in this sentence 'this PAIR of pants' replaces CA(it) and becomes the subject/TE is the pronoun/ and VA 3rd person singular of aller. You have a similar kind of idiom with "how are you" being translated to french as 'ca va bien' "is it going well?"