Bungles (5)
'bungles' is the definition.
(muff is a kind of bungle)
This is the entire clue.
(Other definitions for muffs that I've seen before include "Hand-warmers" , "hand warmers" , "Deals clumsily with" .)
'bungles' is the definition.
('mess up' can be a synonym of 'bungle')
This is the entire clue.
(Another definition for messes up that I've seen is " Mishandles a situation".)