Label Monster Munch packs (4)
I believe the answer is:
term
'label' is the definition.
(I know that be known as is the is a more specific form of the action of term.)
'monster munch packs' is the wordplay.
'packs' indicates a hidden word (I've seen 'packing' mean this).
'TERM' is hidden within 'monster munch'.
(Other definitions for term that I've seen before include "School time; word" , "what being 9 [PREGNANT] leads to?" , "expected time of delivery" , "A fixed or limited time - or an expression" , "Call" .)