Lacking professional expertise (7)
I believe the answer is:
amateur
'lacking professional expertise' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for amateur that I've seen before include "lacking professionalism" , "Person who does something as a pastime rather than a profession" , "Dilettante: buff" , "lacking professional expertise" , "he won't get paid" .)