Not inclined to be honest (2,3,5)
I believe the answer is:
on the level
'honest' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for on the level that I've seen before include "Some horse racing is" , "Honest - genuine" , "No tipping" , "Fair; honestly speaking" , "Honest, truthful (colloq.)" .)