Second race, with number two going badly as the roar goes up? (9)
I believe the answer is:
crescendo
'as the roar goes up?' is the definition.
(musical effect)
'second race with number two going' is the wordplay.
'race' is an anagram indicator (I've seen 'racing' mean this (to race around can mean to move)).
'with' is an insertion indicator.
'number two going' becomes 'cre' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'second' is an anagram of 'scendo'.
'scendo' going around 'cre' is 'CRESCENDO'.
'badly' is the link.
This may not be correct. It may belong to another bit of the clue.
(Other definitions for crescendo that I've seen before include "Intensify" , "Growing louder (mus.)" , "(Of music) gradually increasing in loudness" , "increase in sound level" , "Gradually increasing in volume" .)