Snub portion (3)
I believe the answer is:
cut
I believe this clue is a double definition.
'snub' is the first definition.
(I know that snub can be written as cut)
'portion' is the second definition.
(cut is a kind of portion)
(Other definitions for cut that I've seen before include "Divide; intersect" , "Make an incision" , "Stop filming" , "Saw" , "Hacked off" .)