Granny eats starter of antipasti, with money for side order (4,5)
I believe the answer is:
naan bread
'for side order' is the definition.
'granny eats starter of antipasti with money' is the wordplay.
'granny' becomes 'nan'.
'eats' means one lot of letters goes inside another.
'starter of' indicates taking the first letters.
'with' says to put letters next to each other.
'money' becomes 'bread' (bread is slang for money).
The initial letter of 'antipasti' is 'a'.
'nan' enclosing 'a' is 'naan'.
'naan'+'bread'='NAAN BREAD'
(Other definitions for naan bread that I've seen before include "Indian food item" , "Teardrop-shaped accompaniment to an Indian dish" , "Indian staple?" .)