Kevin is sorry over employing barman (7)
I believe the answer is:
rossini
'barman' is the definition.
(Rossini matches up with the definition barman)
'kevin is sorry over employing' is the wordplay.
'employing' indicates a hidden word (the answer is used or employed by the clue).
'over' is a reversal indicator.
'inissor' can be found hidden inside 'kevin is sorry'.
'inissor' backwards is 'ROSSINI'.
(Other definitions for rossini that I've seen before include "He composed operas" , "Italian scorer" , "opera producer" , "whose barber was in Seville" , "Staff writer" .)