Jailbird with kind companion (7)
I believe the answer is:
consort
'companion' is the definition.
(I know that companion is a kind of consort)
'jailbird with kind' is the wordplay.
'jailbird' becomes 'con' (convict).
'with' is a charade indicator (letters next to each other).
'kind' becomes 'sort' (synonyms).
'con'+'sort'='CONSORT'
(Other definitions for consort that I've seen before include "Husband or wife of a monarch" , "A monarch's spouse" , "Hang out with" , "Marriage partner" , "Monarch's husband" .)