Chew and be swallowing it (4)
I believe the answer is:
bite
'chew' is the definition.
(thesaurus)
'be swallowing it' is the wordplay.
'swallowing' is an insertion indicator.
'be' enclosing 'it' is 'BITE'.
'and' acts as a link.
(Other definitions for bite that I've seen before include "Take bait; sting" , "Injury from teeth" , "Grip; take effect" , "Quick snack" , "Morsel" .)