Hideaway for sound currency (5)
I believe the answer is:
cache
'hideaway' is the definition.
(thesaurus)
'sound currency' is the wordplay.
'sound' indicates a 'sounds like' (homophone) clue.
'currency' becomes 'cash' (cash is a kind of currency).
'cash' is a homophone of 'CACHE'.
'for' acts as a link.
(Other definitions for cache that I've seen before include "Reserve" , "Stockpile" , "Nest egg" , "Put away" , "Hiding-place for treasure etc" .)