Cross-country running finally leaving Nina tolerating exercising (13)
I believe the answer is:
international
'cross-country' is the definition.
'running finally leaving nina tolerating exercising' is the wordplay.
I cannot quite see how this works, but
'running' could be 'on' (I've seen this in other clues) and 'on' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for international that I've seen before include "See 6" , "Game played between countries" , "Eg, rugby game" , "Match between countries" , "Universal" .)