Boss makes start after change (10)
I believe the answer is:
taskmaster
'boss' is the definition.
(I have seen 'hard boss' mean 'taskmaster' so perhaps 'boss' could also mean 'taskmaster')
'makes start after change' is the wordplay.
'after change' indicates an anagram.
'makes'+'start'='makesstart'
'makesstart' is an anagram of 'TASKMASTER'.
(Other definitions for taskmaster that I've seen before include "One in charge of jobs (usually hard)" , "One supervising" , "One imposing heavy workload" , "hard boss" , "Disciplinarian" .)