He’ll do a trim job (6)
I believe the answer is:
barber
'trim job' is the definition.
'barber' can be an answer for 'trim' (thesaurus). I'm unsure of the 'job' bit.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for barber that I've seen before include "Coiffeur" , "One who cuts hair" , "Hair trimmer" , "Hair cutter" , "Men's haircutter, musically of Seville?" .)