Metropolitan ignores trial on speed (5)
I believe the answer is:
tempo
'speed' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for tempo that I've seen before include "What a metronome provides" , "(Musically) the speed to be played" , "Rhythm of piece of music" , "Muscial time" , "Beat (music)" .)