Commit criminal offence accepting gaol initially (7)
I believe the answer is:
consign
'commit' is the definition.
(consigning is a kind of commiting)
'criminal offence accepting gaol initially' is the wordplay.
'criminal' becomes 'con' (abbreviation for 'convict'**).
'offence' becomes 'sin' (I've seen this before).
'accepting' indicates putting letters inside.
'initially' suggests taking the first letters.
The initial letter of 'gaol' is 'g'.
'sin' enclosing 'g' is 'sign'.
'con'+'sign'='CONSIGN'
(Other definitions for consign that I've seen before include "Deliver (to someone's custody)" , "A PM; a race since 1780" , "Hand over (to the Post Office?)" , "Commit or deliver formally" , "Give over for safekeeping" .)