Wilt and fall over nothing (5)
I believe the answer is:
droop
'wilt' is the definition.
(I know that wilt can be written as droop)
'fall over nothing' is the wordplay.
'fall' becomes 'drop' (dropping is a kind of falling).
'over' indicates putting letters inside.
'nothing' becomes 'O' (looks like zero - 0).
'drop' enclosing 'o' is 'DROOP'.
'and' acts as a link.
(Other definitions for droop that I've seen before include "languish" , "Grow faint" , "Sag wearily" , "be despondent" , "Hang down loosely" .)