Short race arranged for musicians (9)
I believe the answer is:
orchestra
'for musicians' is the definition.
(I've seen this before)
'short race arranged' is the wordplay.
'arranged' indicates an anagram (letters rearranged).
'short'+'race'='shortrace'
'shortrace' with letters rearranged gives 'ORCHESTRA'.
(Other definitions for orchestra that I've seen before include "An assembly of musicians with various instruments" , "LSO, for example" , "Large band of players" , "Large band playing classical music" , "in four sections" .)