Given a start, I had come ninth in it (8)
I believe the answer is:
alphabet
'given a' is the definition.
I can't judge whether this defines the answer.
'start i had come ninth in it' is the wordplay.
I cannot really see how this works, but
'start' could be 'alpha' (alpha is a kind of start) and 'alpha' is found within the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
The remaining letters 'be' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for alphabet that I've seen before include "ABC" , "A-Z" , "Whole set of letters" , "Letters, symbols used in a writing system" , "needing help on mountain height" .)