Become limp, droop (4)
I believe the answer is:
wilt
I believe this is a double definition.
'become limp' is the first definition.
(synonyms)
'droop' is the second definition.
(I know that droop can be written as wilt)
(Other definitions for wilt that I've seen before include "tire?" , "Flag" , "Lose strength and become limp" , "(Of plant) become limp" , "Decline" .)