Try for a fly (4)
I believe the answer is:
swat
'try for a fly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for swat that I've seen before include "Twas something of a blow" , "District of Pakistan; sharp blow" , "deliver blow" , "Swift, sharp blow" , "Crush (eg, a fly)" .)