Musical tempo (7)
I believe the answer is:
allegro
'musical tempo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for allegro that I've seen before include "A fast piece of work" , "In quick time" , "Lively, quick (mus.)" , "Quick (of a score)" , "'Brisk and lively, musically (7)'" .)