Dynamic person is good in bank (5)
I believe the answer is:
tiger
'dynamic person' is the definition.
(tiger can mean an ambitious or dynamic person)
'good in bank' is the wordplay.
'good' becomes 'g' (abbreviation).
'in' is an insertion indicator.
'bank' becomes 'tier' (both can mean a row of similar things).
'g' placed into 'tier' is 'TIGER'.
'is' is the link.
(Other definitions for tiger that I've seen before include "Dangerous animal" , "Large striped cat" , "Beast as Shere Khan" , "Asian animal" , "audacious person" .)