Some macaroni one mixes with vegetable (5)
I believe the answer is:
onion
'vegetable' is the definition.
(onion is a vegetable)
'some macaroni one mixes' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'ONION' can be found hidden inside 'macaroni one mixes'.
'with' is the link.
(Other definitions for onion that I've seen before include "Plant with edible bulb" , "Alliaceous plant" , "Edible tear-jerker" , "Hot dog topping" , "Type of allium" .)