Stockpile (5)

(Other definitions for stash that I've seen before include "Secret(ly) store" , "Stow; secret store" , "(Hidden store of) drugs" , "Stow away" , "Treasure trove" .)
'stockpile' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for amass that I've seen before include "Sodium chloride" , "Gather together, pile up" , "Gather in great quantity" , "Build up" , "Accumulate, pile up" .)