Door security (7)
I believe the answer is:
padlock
'door security' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for padlock that I've seen before include "E.g. shed, moneybox, fastener" , "Detachable security device" , "Security device with key" , "Security fastener" , "security measure" .)