Crossword Genius

A hundred up for a prize? (3)

Ross

I believe the answer is:

cup

'for a prize?' is the definition.
(cup is a kind of prize)

'a hundred up' is the wordplay.
'a hundred' becomes 'c' (Roman numeral).
'c'+'up'='CUP'

(Other definitions for cup that I've seen before include "Trophy, drink" , "Chalice; trophy" , "Beaker" , "Sort of cake" , "Container to drink from - prize" .)

I've seen this clue in The Times.
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