Order bloke to wear top (6)
I believe the answer is:
behest
'order' is the definition.
(I've seen this before)
'bloke to wear top' is the wordplay.
'bloke' becomes 'he' ('he' refers to a man).
'to wear' is an insertion indicator (to wear something is to be covered up by it).
'top' becomes 'best' (associated in meaning).
'he' inserted within 'best' is 'BEHEST'.
(Other definitions for behest that I've seen before include "Command, bidding" , "Order" , "Command - Thebes (anag)" , "(At someone's) command" .)