Air which can invigorate the long-distance runner (5,4)

'can invigorate the long-distance runner' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'air' is the wordplay.
I cannot really see how this works, but
'air' could be 'wind' and 'wind' is found within the answer.
The remaining letters 'fresh' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'which' is the link.

Can you help me to learn more?