They are walking (8)
I believe the answer is:
ambulant
'are walking' is the definition.
(thesaurus)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for ambulant that I've seen before include "Walking, moving around" , "Of patient, able to walk" , "Able to walk, not confined to bed" , "Moving about, able to walk" .)