Run on the level (5)
I believe the answer is:
legit
This clue might be a double definition.
'run' is the first definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I can't see?
'on the level' is the second definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for legit that I've seen before include "In accordance with the law (abbr)" , "Run away - above board (colloq)" , "Genuine" , "not unlawful" , "Not illegal" .)