Being edgy or touchy, it makes rugby players jump! (4-3)
I believe the answer is:
line-out
'jump' is the definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I don't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for line-out that I've seen before include "RU throw-in" , "A rugby formation to receive throw-in" , "Outline for a rugby formation" , "Rugby re-start" , "Method of restarting play in rugby" .)