They're put down on canvas? Beat one's that's run out of craft in the main? (8)

I believe the answer is:

oilslick

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

'one's that's run out of craft in the main?' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'they're put down on canvas? beat' is the wordplay.
'they're put down on canvas?' becomes 'oils' (oil paints).
'beat' becomes 'lick' (synonyms).
'oils'+'lick'='OILSLICK'

Can you help me to learn more?

I've seen this clue in The Guardian.

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.