Manager starts to back off somewhat sharpish (4)
I believe the answer is:
boss
'manager' is the definition.
(I've seen this before)
'starts to back off somewhat sharpish' is the wordplay.
'starts to' suggests taking the first letters.
The initial letters of 'back off somewhat sharpish' is 'BOSS'.
(Other definitions for boss that I've seen before include "Stud; employer" , "Head honcho" , "One in charge; stud" , "excellent American > stud" , "Domineer" .)