Crossword Genius

Train, please, on two-thirds of RAF jets? (10)

Ross

I believe the answer is:

aeroplanes

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'jets?' is the definition.
(jet is a kind of aeroplane)

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for aeroplanes that I've seen before include "Fliers" , "Aircraft" .)

I've seen this clue in The Telegraph.
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