Thick-skinned heavyweight who charges money (5)
I believe the answer is:
rhino
I believe this is a double definition.
'thick-skinned heavyweight who charges' is the first definition.
(thick-skinned animal which may charge)
'money' is the second definition.
(old-fashioned slang term for money)
(Other definitions for rhino that I've seen before include "Horned animal; money (slang)" , "old money?" , "Horned creature" , "Moola" , "Large animal with a horn on its snout, in short" .)