Get morsel to chew as filling (4,2)
I believe the answer is:
beat it
'get' is the definition.
(thesaurus)
'morsel to chew as filling' is the wordplay.
'morsel' becomes 'bit' (synonyms).
'to chew' becomes 'eat' (I've seen this before).
'as filling' means one lot of letters goes inside another.
'bit' going around 'eat' is 'BEAT IT'.
(Other definitions for beat it that I've seen before include "Scarper" , "Scram, take a powder" , "Scram, get lost" , "fly away" , "try out drum kit?" .)