Light on one's feet now? (8)
I believe the answer is:
dismount
'light' is the definition.
(I know that light can be written as dismount)
'one's feet now?' is the wordplay.
I cannot really see how this works, but
'one's' could be 'is' (Roman numeral) and 'is' is found within the answer.
This explanation may well be incorrect...
'on' is the link.
Can you help me to learn more?
(Other definitions for dismount that I've seen before include "Get down, from bike or horse" , "Get off a horse/bicycle" , "Desert Arab perhaps" , "Cease to ride" , "Alight from a horse or bicycle" .)