No sub can be a bounty (5)
I believe the answer is:
bonus
'a bounty' is the definition.
(thesaurus)
'no sub can be' is the wordplay.
'can be' indicates anagramming the letters.
'no'+'sub'='nosub'
'nosub' with letters rearranged gives 'BONUS'.
(Other definitions for bonus that I've seen before include "Additional wage" , "Sum added to salary for good performance" , "Extra income" , "Additional payment for work, often on merit" , "Extra money paid on top of salary" .)