Male animal that may be made fast? (4)
I believe the answer is:
buck
I believe this is a double definition.
'male animal' is the first definition.
(I've seen this before)
'that may be made fast?' is the second definition.
(as in 'making a fast buck', making money quickly)
(Other definitions for buck that I've seen before include "Go against" , "Stag" , "may stop here and > be passed" , "impetuous youth" , "Male rabbit, deer etc" .)