Crossword Genius

Join (5)

Ross

There are a few possibilities for this:

Which length description are you looking for?:

4

5

6 7 3*

(Another definition for optin that I've seen is " Decide to take part".)

I've seen this clue in The Irish Independent, The Guardian, The Telegraph, the LA Times, The Sun, the Penny Press, The Mirror, The Star Tribune, The New York Times, the Universal and 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.