Figuratively, a couple of crosses (6)

I believe the answer is:

twenty

I'm a little stuck... Click here to teach me more about this clue!

'couple of crosses' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Maybe there's an association between them I don't understand?

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for twenty that I've seen before include "One score" , "John B Keane wrote about many young men of this age" , "Hundredweights to a ton" , "previous clue?" , "made by Q on a light blue square" .)

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.