The critical point in eating a biscuit? (6)
I believe the answer is:
crunch
'the critical point' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for crunch that I've seen before include "Informally, a decisive event or showdown" , "Crush with the teeth" , "Process (lots of data)" , "Crush noisily" , "Chew something hard" .)