Put down and leave a jacket (5)
I believe the answer is:
parka
'a jacket' is the definition.
(I know that parka is a type of jacket)
'put down and leave' is the wordplay.
'put' becomes 'park' (parking is a kind of putting).
'down' becomes 'dn'.
'leave' indicates named letters should be taken away.
'and' with 'dn' taken out is 'a'.
'park'+'a'='PARKA'
(Other definitions for parka that I've seen before include "Windproof jacket" , "warm gear" , "jacket for cold weather" , "Warm, hooded coat" , "Hooded warm jacket" .)