Look favourably upon second third of a league (5)
I believe the answer is:
smile
'look' is the definition.
(I know that smile is a type of look)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for smile that I've seen before include "Pleased expression" , "Happy facial expression" , "Indicate pleasure with lips movement" , "Show happiness" , "Friendly facial gesture" .)