Munch away at a piece of biscuit (5)
I believe the answer is:
scoff
'munch' is the definition.
Although both the answer and definition are verbs in their base form, I cannot understand how they can define each other.
'away at a piece of biscuit' is the wordplay.
'away' becomes 'off' (synonyms).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'a piece of biscuit' becomes 'sc' (I can't justify this - if you can you should believe this answer much more).
'off' put after 'sc' is 'SCOFF'.
Can you help me to learn more?
(Other definitions for scoff that I've seen before include "Quickly swallow" , "food on offer" , "turtle soup for example?" , "taunt" , "Devour (informal)" .)