Hidden away (7)
I believe the answer is:
'hidden away' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stashed that I've seen before include "hidden from view" , "'Hoarded, squirrelled away (7)'" , "hidden away" , "Saved up for future use" , "Stored away in a safe place" .)