Rugby supporter? (4)

I believe the answer is:

prop

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This might be a double definition.

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

'supporter?' is the second definition.
(I've seen this before)

Can you help me to learn more?

(Other definitions for prop that I've seen before include "Support - item on stage" , "Temporary support" , "Stay" , "Front row forward" , "Support; object used on stage" .)

I've seen this clue in the Evening Standard.

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