Butch is said to be a match for nothing (5)

I believe the answer is:
macho
'butch' is the definition.
(synonyms)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for macho that I've seen before include "Affectedly virile" , "Like aggressive male" , "Exaggeratedly masculine" , "Blokeish" , "Aggressively male" .)