Having no inclination whatsoever - honest (2,3,5)
I believe the answer is:
on the level
'honest' is the definition.
(I've seen this before)
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 "Honest - genuine" , "No tipping" , "Fair; honestly speaking" , "Some horse racing is" , "Honest, truthful (colloq.)" .)