Fall from heights again (3)
I believe the answer is:
sag
'fall' is the definition.
(I've seen this before)
'from heights again' is the wordplay.
'from' says the answer is hidden in the clue.
'SAG' is hidden in the letters of 'heights again'.
(Other definitions for sag that I've seen before include "Lose energy" , "Subsidence" , "Decline" , "Slump" , "Sinking" .)