Additional part (10)
I believe the answer is:
supplement
(Other definitions for supplement that I've seen before include "Something added" , "Extra" , "Add to; newspaper section" , "Add-on" , "Boost" .)
I've seen this clue in the Evening Standard.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free.
Check out my app
or
learn more
about the Crossword Genius project.