16d -Agent =rep(representative) Roof =top of building -Reproof
18d Finish +end - orse anagram of Sore -Endorse
1a If hip you could be described as a Cool cat + hipster is a style of pants
1a In my day cool cats wore hipsters!
16d Rep is the agent ,roof is top of the building and the whole word is an admonishment.
Finish is end and orse is anag of sore and endorse is to back something.