Some denigrate MP over time (5)
I believe the answer is:
tempo
'time' is the definition.
(tempo is a kind of time)
'some denigrate mp over' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'TEMPO' is hidden within 'denigrate mp over'.
(Other definitions for tempo that I've seen before include "Rhythm of piece of music" , "(Musically) the speed to be played" , "Time (music)" , "Musical time" , "musical quality?" .)