Throw gym student first time (4)
I believe the answer is:
pelt
'throw' is the definition.
(I know that pelt is a more specific form of the action the throw)
'gym student first time' is the wordplay.
'gym' becomes 'pe' (short for Physical Education).
'student' becomes 'l' (as in L-plates for learner drivers).
'first time' becomes 't' (lst letter of 'time').
'pe'+'l'+'t'='PELT'
(Other definitions for pelt that I've seen before include "Hairy coat of a mammal" , "Skin of a fur-bearing mammal" , "Animal hide" , "Skin - bombard - hurry!" , "Run fast - rain hard" .)