2013 novel by William Boyd (4)

I believe the answer is:

solo

(Other definitions for solo that I've seen before include "Unaccompanied flight" , "Aline in Oslo" , "Done by one person" , "Unaccompanied - card game" , "Fly aircraft" .)

I've seen this clue in The Mirror.

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.