Greg's associate Tim (6)
I believe the answer is:
henman
'greg's' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'associate tim' is the wordplay.
I cannot really see how this works, but
'associate' could be 'an' (AN is an example) and 'an' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for henman that I've seen before include "Tim -, tennis player" , "Former racketeer" .)