Restart of rugby game for ex-student? (4-3)

I believe the answer is:

drop-out

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'student?' is the definition.
(I have seen 'Unsuccessful student' mean 'drop-out' so perhaps 'student' could also mean 'drop-out')

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for drop-out that I've seen before include "Unsuccessful student" , "start at Rugby" .)

I've seen this clue in The Times.

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