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 within the letters.
However, I'm uncertain 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 Evening Standard and The Globe and Mail.

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