How about "Clientes in taberna sunt." If the verb ends up primarily at the end of the sentence--pronoun, object/noun, verb or object (pronoun/verb)
That is technically correct, however the verb 'esse' or 'to be' tends to go between the two nouns it is coupling together
'sunt' is merely the the 3rd person plural form of 'esse'
What's wrong with "clientes in caupona sunt"?
And so what's wrong with clientes in taverna sunt? Duo caprice again?
A tavern in English is not a shop but an Inn , why do you not accept caupona to translate tavern into Latin?