Admits every wrongdoing involving heartless outlaw (6,2)

'admits' is the definition.
('allow in' can be a synonym of 'admit')

'every wrongdoing involving heartless outlaw' is the wordplay.
'every' becomes 'all' (similar in meaning).
'wrongdoing' becomes 'sin' (sin is a kind of wrongdoing).
'involving' means one lot of letters goes inside another.
'heartless' suggests removing the centre.
'outlaw' with its middle taken out is 'ow'.
'all'+'sin'='allsin'
'allsin' enclosing 'ow' is 'ALLOWS IN'.