Admittedly worked hard having change of heart (7)
I believe the answer is:
granted
'admittedly' is the definition.
(I've seen this before)
'worked hard having change of heart' is the wordplay.
I cannot quite understand how this works, but
'worked' could be 'ran' (eg a machine that works is running) and 'ran' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for granted that I've seen before include "Admittedly; gave formally" , "Admittedly; given" , "One doesn't like being taken for it" , "Admitted" , "OK - allowed" .)