Crossword Genius

One of two bound for power (4)

Ross

I believe the answer is:

prop

'one of two bound' is the definition.
(rugby)

'for power' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'power' becomes 'p' (symbol in physics).
'pro'+'p'='PROP'

(Other definitions for prop that I've seen before include "Object used on the set of a play" , "Support; object used on stage" , "Shore for 4 down" , "Set piece" , "Moveable object used on stage" .)

I've seen this clue in The Guardian.
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