In business, a swell thing to do (6)
I believe the answer is:
expand
'do' is the definition.
The definition and answer 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 don't see?
'in business a swell thing' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'to' acts as a link.
Can you help me to learn more?
(Other definitions for expand that I've seen before include "Become larger or more extensive" , "Mushroom" , "Grow bigger" , "Distend" , "increasingly elaborate" .)