Pressure in bank to respond (5)
I believe the answer is:
reply
'to respond' is the definition.
(synonyms)
'pressure in bank' is the wordplay.
'pressure' becomes 'p' (abbreviation).
'in' is an insertion indicator.
'bank' becomes 'rely' (to bank on is to rely on).
'p' inserted within 'rely' is 'REPLY'.
(Other definitions for reply that I've seen before include "Comeback" , "acknowledgement" , "Return" , "Answer, respond" , "response is demanded" .)