Crossword Genius

Grab sack and ignite (9)

Ross

I believe the answer is:

catchfire

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'ignite' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'grab sack' is the wordplay.
'grab' becomes 'catch' (synonyms).
'sack' becomes 'fire' (both can mean to dismiss from a job).
'catch'+'fire'='CATCHFIRE'

'and' is the link.

Can you help me to learn more?

I've seen this clue in The Daily Express.
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