Pig swallowing the whole of the pasty (6)
I believe the answer is:
sallow
'the pasty' is the definition.
(thesaurus)
'pig swallowing the whole of' is the wordplay.
'pig' becomes 'sow' (I've seen this before**).
'swallowing' is an insertion indicator.
'the whole of' becomes 'all' (I've seen this in other clues).
'sow' going around 'all' is 'SALLOW'.
(Other definitions for sallow that I've seen before include "Pale or yellowish colour" , "Pale; sickly" , "of a pale yellow or brown colour" , "Unhealthy looking" , "Shrubby tree" .)