Layer is raised in storehouse (7)
I believe the answer is:
deposit
'layer' is the definition.
(I've seen this before)
'is raised in storehouse' is the wordplay.
'raised' says the letters should be written backwards (going up in a down clue).
'in' means one lot of letters goes inside another.
'storehouse' becomes 'depot' (synonyms).
'is' backwards is 'si'.
'si' going inside 'depot' is 'DEPOSIT'.
(Other definitions for deposit that I've seen before include "Money up front" , "Hoard" , "(Money) laid down" , "Down payment made to secure goods" , "Money in bank - part payment" .)