Participant used Iraqi fuel (9)

I believe the answer is:

qualifier

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

'participant' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

'used iraqi fuel' is the wordplay.
'used' indicates an anagram.
'iraqi'+'fuel'='iraqifuel'
'iraqifuel' is an anagram of 'QUALIFIER'.

Can you help me to learn more?

(Other definitions for qualifier that I've seen before include "heat" , "Contestant who meets the basic requirements" .)

I've seen this clue in The Daily Express.

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