Like Jack and Jill, they are non winners (7-2)
I believe the answer is:
runners-up
'non winners' is the definition.
The answer and definition can be both people as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
'like jack and jill they' is the wordplay.
I cannot quite understand how this works, but
'jack' could be 'runner' (runner is a kind of jack) and 'runner' is located in the answer.
The remaining letters 'sup' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'are' is the link.
Can you help me to learn more?
(Other definitions for runners-up that I've seen before include "Those in second place" , "Silver medallists" , "Those finishing second" , "Those placed second" , "They get silver" .)