Store money, did you say? (5)
I believe the answer is:
cache
'store' is the definition.
(cache is a kind of store)
'money did you say?' is the wordplay.
'money' becomes 'cash' (I've seen this before).
'did you say?' indicates a 'sounds like' (homophone) clue.
'cash' is a homophone of 'CACHE'.
(Other definitions for cache that I've seen before include "Hiding place for treasure or store" , "Secret store of valuables" , "Hiding place for treasure or stores" , "Hidden storage space" , "(Place in) hidden store" .)