Gasp (4)
'gasp' is the definition.
(I know that gasp can be written as pant)
This is all the clue.
(Other definitions for pant that I've seen before include "Breath noisily from exertion" , "Breath rapidly" , "Breathe noisily after running" , "Gasp for breath (like a hot dog?)" , "Struggle for breath" .)