Hiker takes stroll between two rivers (7)
I believe the answer is:
rambler
'hiker' is the definition.
(I've seen this before)
'stroll between two rivers' is the wordplay.
'two rivers' means two replacements for 'river'.
'stroll' becomes 'amble' (synonyms).
'between' indicates putting letters inside.
'river' becomes 'r' (abbreviation for river).
'river' becomes 'r' (abbreviation for river).
'r'+'r'='rr'
'amble' placed within 'rr' is 'RAMBLER'.
'takes' acts as a link.
(Other definitions for rambler that I've seen before include "Type of rose" , "Straggling rose" , "Person whose speech is long and disorganised" , "Rose maybe" , "country activist" .)