High-flying sport (7)
I believe the answer is:
skylark
'high-flying sport' is the definition.
The answer and definition can be both to do with motion as well as being verbs in their base form.
Maybe you can see a link between them that I can't see?
'flying sport' is the wordplay.
'flying' becomes 'sky' (I can't explain this - if you can you should give a lot more credence to this answer).
'sport' becomes 'lark' (synonyms).
'sky'+'lark'='SKYLARK'
Can you help me to learn more?
(Other definitions for skylark that I've seen before include "Bird that sings aloft" , "very high singer" , "Passerine bird" , "Common songbird" , "High-flying songbird" .)