A walker? That's right, a walker (7)
I believe the answer is:
rambler
'a walker?' is the definition.
(I know that Rambler is a type of walker)
'right a walker' is the wordplay.
'right' becomes 'r' (common abbreviation).
'a walker' becomes 'ambler' (I've seen this before).
'r'+'ambler'='RAMBLER'
'that's' is the link.
(Other definitions for rambler that I've seen before include "Presumably one goes on" , "Type of rose" , "Periodical" , "Person whose speech is long and disorganised" , "One who goes on country walks" .)