In a frenzy, melted protein (6)
I believe the answer is:
enzyme
'protein' is the definition.
(enzyme is a kind of protein)
'in a frenzy melted' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ENZYME' can be found hidden inside 'frenzy melted'.
(Other definitions for enzyme that I've seen before include "causing ferment" , "Biological catalyst" , "Protein produced by living cell" , "Protein product of living cells" , "Substance created in living cells acting as a catalyst" .)