Security is brought back into warehouse (7)
I believe the answer is:
deposit
'security' is the definition.
(I know that deposit is a type of security)
'is brought back into warehouse' is the wordplay.
'brought back' is a reversal indicator.
'into' indicates putting letters inside.
'warehouse' becomes 'depot' (I've seen this in another clue).
'is' reversed gives 'si'.
'si' placed within 'depot' is 'DEPOSIT'.
(Other definitions for deposit that I've seen before include "is one back on the bottle?" , "fur, possibly" , "Part payment on a purchase" , "Money in bank - part payment" , "Layer laid down" .)