Ruffian who loses head playing in goal (8)
I believe the answer is:
hooligan
'ruffian' is the definition.
(I know that hooligan is a class)
'who loses head playing in goal' is the wordplay.
'loses head' means to remove the first letter.
'playing' indicates an anagram.
'who' with its initial letter taken away is 'ho'.
'in'+'goal'='ingoal'
'ingoal' with letters rearranged gives 'oligan'.
'ho'+'oligan'='HOOLIGAN'
(Other definitions for hooligan that I've seen before include "Thug, ruffian" , "Lawless type" , "Destructive or badly-behaved youth" , "Antisocial rough" , "Violent lout" .)