He works his hours to suit his customers (6)
I believe the answer is:
tailor
'suit his customers' is the definition.
'tailor' can be an answer for 'suit' (thesaurus). I'm not sure about the 'his customers' bit.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for tailor that I've seen before include "Rialto (anag) -- adjust to a specific need" , "Maker of clothes for men" , "Fashion" , "One makes suits etc. to measure" , "Couturier" .)