Ace bloke for being representative (5)
I believe the answer is:
agent
'representative' is the definition.
(agent is a kind of representative)
'ace bloke' is the wordplay.
'ace' becomes 'a'.
'bloke' becomes 'gent' (I've seen this in other clues).
'a'+'gent'='AGENT'
'for being' is the link.
(Other definitions for agent that I've seen before include "Catalyst" , "One's representative" , "Salesman" , "Business manager" , "Actor" .)