Employer of a superior, fault free service (4)
I believe the answer is:
user
'employer' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for user that I've seen before include "Utiliser" , "Drug taker" , "Patron" , "Maybe one needing pot" , "Tech support caller?" .)