Incentive: British taking responsibility? (5)
I believe the answer is:
bonus
'incentive' is the definition.
(synonyms)
'british taking responsibility?' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'taking' says to put letters next to each other.
'responsibility?' becomes 'onus' (onus is a duty or responsibility).
'b'+'onus'='BONUS'
(Other definitions for bonus that I've seen before include "Extra payment - reward" , "Something more than you expected" , "Extra payment for good work" , "Payment additional to the expected or usual" , "Additional incentive payment" .)