Warehouse is put back in down payment (7)
I believe the answer is:
deposit
'down payment' is the definition.
(synonyms)
'warehouse is put back in' is the wordplay.
'warehouse' becomes 'depot' (I've seen this before).
'put back' says the letters should be written backwards.
'in' indicates putting letters inside.
'is' written backwards gives 'si'.
'depot' going around 'si' is 'DEPOSIT'.
(Other definitions for deposit that I've seen before include "store" , "Posited as down payment" , "Lay down" , "Drop" , "Put down - initial payment" .)