Drop in numbers a godsend (3)
I believe the answer is:
sag
'drop' is the definition.
(I know that sag is a more specific form of the action drop)
'in numbers a godsend' is the wordplay.
'in' says the answer is hidden in the clue.
'SAG' can be found hidden inside 'numbers a godsend'.
(Other definitions for sag that I've seen before include "Drop" , "Sink under weight" , "Droop, sink in the middle" , "fall" , "Cave in" .)