Plate, unusually, is sprung (5)
I believe the answer is:
leapt
'is sprung' is the definition.
(I've seen this in another clue)
'plate unusually' is the wordplay.
'unusually' is an anagram indicator.
'plate' anagrammed gives 'LEAPT'.
(Other definitions for leapt that I've seen before include "gone up dramatically" , "rose fast" , "Jumped a long way" , "moved up quickly" , "Took off" .)