Admit everything with cry of pain (5)
I believe the answer is:
allow
'admit' is the definition.
(allowing is a kind of admiting)
'everything with cry of pain' is the wordplay.
'everything' becomes 'all' (I've seen this before).
'with' means one lot of letters go next to another.
'cry of pain' becomes 'ow' (I've seen this in other clues).
'all'+'ow'='ALLOW'
(Other definitions for allow that I've seen before include "Permit, let happen" , "Permit or acknowledge" , "Tolerate" , "Licence" , "OK" .)