It's just Frank? (2,3,5)
I believe the answer is:
on the level
'frank?' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for on the level that I've seen before include "Fair; honestly speaking" , "Some horse racing is" , "Honest - genuine" , "No tipping" , "Honest, truthful (colloq.)" .)