Diamond steeplechaser with odds fixed on run (8)
I believe the answer is:
sparkler
'diamond' is the definition.
(something which sparkles)
'steeplechaser with odds fixed on run' is the wordplay.
'steeplechaser' becomes 'arkle' (I have seen 'Famous steeplechaser ' mean 'arkle' so perhaps 'steeplechaser' could also mean 'arkle').
'with' is a charade indicator (letters next to each other).
'odds' becomes 'sp' (betting abbreviation for starting price).
'fixed on run' becomes 'r' (I can't explain this - if you can you should believe this answer much more).
'arkle' put after 'sp' is 'sparkle'.
'sparkle'+'r'='SPARKLER'
Can you help me to learn more?
(Other definitions for sparkler that I've seen before include "Firework or diamond ring" , "Jewel" , "Slow-burning firework and a diamond" , "Bright gem" , "Diamond (colloq.)" .)