Legitimate walk (14)
I believe the answer is:
constitutional
I believe this is a double definition.
'legitimate' is the first definition.
(thesaurus)
'walk' is the second definition.
(I know that constitutional is a type of walk)
(Other definitions for constitutional that I've seen before include "healthy exercise" , "Healthy walk" , "Regular walk" , "For lawyer, perfectly good" , "Governmental" .)