Some nominate MP on time (5)
I believe the answer is:
tempo
'time' is the definition.
(I know that tempo is a type of musical time)
'some nominate mp on' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'TEMPO' is hidden within 'nominate mp on'.
(Other definitions for tempo that I've seen before include "musical quality?" , "Speed or beat, musically" , "Speed of a musical piece" , "Pace of a piece of music" , "Musical beat or rhythm" .)