Knock off bails, ultimately getting duck (5)
I believe the answer is:
steal
'knock off' is the definition.
(synonyms)
'bails ultimately getting duck' is the wordplay.
'bails ultimately' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'getting' is a charade indicator (letters next to each other).
'duck' becomes 'teal' (teal is a kind of duck).
's'+'teal'='STEAL'
(Other definitions for steal that I've seen before include "Take without permission" , "Snatch" , "Appropriate" , "Whip" , "Walk off with" .)