Outpaced by quicker runners, having failed to get a seat! (4,8)
I believe the answer is:
left standing
'outpaced by quicker runners having failed to' is the definition.
I can't judge whether this definition defines the answer.
'a seat' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is found in the answer.
This explanation may well be incorrect...
'get' acts as a link.
Can you help me to learn more?
(Other definitions for left standing that I've seen before include "Abandoned candidature" , "being too far behind" .)