Friends regularly hiding chap put in custody (6)
I believe the answer is:
remand
'custody' is the definition.
(I know that custody can be written as remand)
'friends regularly hiding chap put in' is the wordplay.
'regularly hiding' indicates alternate letters (letters removed at regular intervals).
'chap' becomes 'man' (chap can mean a man).
'put in' is an insertion indicator.
The alternate letters of 'friends' are 'red'.
'red' going around 'man' is 'REMAND'.
(Other definitions for remand that I've seen before include "Send back, into custody say" , "Commital to custody" , "Place of detention for young offenders" , "Send back into custody or bail" , "Put a defendant on bail or in custody" .)