Promise father a part in the play (6)
I believe the answer is:
parole
'promise' is the definition.
(I know that parole is a type of promise)
'father a part in the play' is the wordplay.
I cannot really understand how this works, but
'father' could be 'pa' (pa can mean dad or father) and 'pa' is present in the answer.
'part' could be 'role' (eg a theatrical role) and 'role' is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for parole that I've seen before include "Temporary release (of a prisoner)" , "Conditional release from imprisonment" , "Early conditional release for prisoner in jail" , "Promise - conditional release" , "Word - condition of liberty" .)