Tar wanting a cat, to whip (7)
I believe the answer is:
trounce
'to whip' is the definition.
('trounce' can be a synonym of 'whip')
'tar wanting a cat' is the wordplay.
'wanting' is a deletion indicator (to want something can mean to lack it or need it).
'cat' becomes 'ounce' (ounce can mean a snow leopard).
'tar' with 'a' taken away is 'tr'.
'tr'+'ounce'='TROUNCE'
(Other definitions for trounce that I've seen before include "Defeat by large margin" , "Wallop" , "Defeat decisively" , "Beat thoroughly on recount" , "Beat badly in recount" .)