Kept in banks is our money (3)
I believe the answer is:
sou
'money' is the definition.
(I've seen this before)
'kept in banks is our' is the wordplay.
'kept in' indicates the answer is hidden within the clue.
'SOU' is hidden within 'banks our'.
(Other definitions for sou that I've seen before include "Tiny amount of money" , "Little money once" , "Very little to spend" , "Something of little worth" , "Former French coin of low value" .)