"Float like a butterfly, sting like a bee" boxer
I believe the answer is:
ali
'float like a butterfly sting like a bee boxer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ali that I've seen before include "Ring' specialist" , "US heavyweight boxer" , "Muhammad - - , legendary boxer" , "Old fighter" , "Muhammad ..., famous boxer" .)