Connoisseur of colour? (4)
I believe the answer is:
buff
This clue is a double definition.
'connoisseur' is the first definition.
(thesaurus)
'colour?' is the second definition.
(buff is a kind of colour)
'of' acts as a link.
(Other definitions for buff that I've seen before include "nude?" , "Light yellow - polishing pad" , "Finish" , "Informal enthusiast - polish him" , "Polish - fan" .)