Picked up money in store (5)
I believe the answer is:
cache
'store' is the definition.
(I know that cache is a type of store)
'picked up money' is the wordplay.
'picked up' shows a homophone (sound like).
'money' becomes 'cash' (cash is a type of money).
'cash' sounds like 'CACHE'.
'in' acts as a link.
(Other definitions for cache that I've seen before include "Hidden storage space" , "Reserve" , "Concealed store" , "memory" , "Secret store, hoard" .)