Prisoner and dog tally (6)
I believe the answer is:
concur
'tally' is the definition.
(thesaurus)
'prisoner and dog' is the wordplay.
'prisoner' becomes 'con' (abbreviation for 'convict').
'and' is a charade indicator (letters next to each other).
'dog' becomes 'cur' (cur is a kind of dog).
'con'+'cur'='CONCUR'
(Other definitions for concur that I've seen before include "share the same opinion" , "See eye to eye" , "run together" , "Be in accord" , "Express agreement" .)