Central character in custody has justification for crime (7)
I believe the answer is:
treason
'for crime' is the definition.
(treason is a kind of crime)
'central character in custody has justification' is the wordplay.
'central character in' says to take the centre.
'has' says to put letters next to each other.
'justification' becomes 'reason' (I've seen this before).
The middle of 'custody' is 't'.
't'+'reason'='TREASON'
(Other definitions for treason that I've seen before include "Betraying one's country" , "One's art? (anag)" , "Betrayal of one's nation" , "Perfidy" , "Offence against state" .)