Last on track are twin high jumpers (8)
I believe the answer is:
knitwear
'last on track' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'are twin high jumpers' is the wordplay.
I cannot quite see how this works, but
an anagram of 'are' is 'ear' which is present in the answer.
an anagram of 'twin' is 'nitw' which is within the answer.
A single letter 'k' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for knitwear that I've seen before include "Sweaters etc" , "'Woolly jumpers, socks etc (8)'" , "Clothing of intertwined wool" , "such as often goes over shirts and blouses" , "sweaters, for example" .)