Outboard propeller (3)

I believe the answer is:

oar

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

'propeller' is the definition.
(an oar helps propel a boat)

'outboard' is the wordplay.
'OAR' is hidden in amongst the letters.
But, I am unsure how this is indicated.

Can you help me to learn more?

(Other definitions for oar that I've seen before include "Rowing blade" , "propels floating craft" , "Crewman" , "that may be feathered?" , "Crew member" .)

I've seen this clue in The Globe and Mail and the Evening Standard.

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