Adhesive to fix mug (3)
I believe the answer is:
gum
'adhesive' is the definition.
(gum is a kind of adhesive)
'fix mug' is the wordplay.
'fix' indicates anagramming the letters.
'mug' is an anagram of 'GUM'.
'to' acts as a link.
(Other definitions for gum that I've seen before include "Glue; jelly-like sweet" , "seal" , "A chopper base" , "To stick with adhesive" , "Chewed sweet" .)