Droopy (4)
I believe the answer is:
limp
'droopy' is the definition.
(I know that droopy can be written as limp)
This is all the clue.
(Other definitions for limp that I've seen before include "Walk badly; not stiff" , "Flaccid" , "Walk haltingly" , "Floppy" , "Walk with an uneven stop" .)