Bags holding northern nibbles (6)
I believe the answer is:
snacks
'nibbles' is the definition.
(I know this)
'bags holding northern' is the wordplay.
'bags' becomes 'sacks' (sack is a kind of bag).
'holding' is an insertion indicator.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'sacks' placed around 'n' is 'SNACKS'.
(Other definitions for snacks that I've seen before include "Light bites such as crisps" , "Nibbles" , "Small food amounts between main meals" , "Light repasts" , "Small or casual meals, often hurried" .)