Money in store, by the sound of it (4)
I believe the answer is:
cash
'money' is the definition.
(cash is a type of money)
'store by the sound of it' is the wordplay.
'store' becomes 'cache' (cache is a kind of store).
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'cache' is a homophone of 'CASH'.
'in' is the link.
(Other definitions for cash that I've seen before include "bread" , "notes, perhaps?" , "Money in the form of notes and coins" , "Ready money" , "Spondulicks" .)