Flip over pupil failing to finish on time (3,2)

I believe the answer is:

tip up

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'flip' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?

'over pupil failing to finish on time' is the wordplay.
'over' is a reversal indicator.
'failing to finish' means to remove the last letter.
'on' is a charade indicator (letters next to each other).
'time' becomes 't' (abbreviation).
'pupil' with its last letter taken off is 'pupi'.
'pupi'+'t'='pupit'
'pupit' in reverse letter order is 'TIP-UP'.

Can you help me to learn more?

(Other definitions for tip up that I've seen before include "overturn" , "More left on plate" .)

I've seen this clue in the Sydney Morning Herald.

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