The most common and most likely answer to this crossword clue is the 7 letter word RAMBLER
I've seen this crossword clue in The Daily Telegraph
R
A
M
B
L
E
R
More clues leading to the result RAMBLER
- Walker who keeps talking incoherently?
- Rover car about to drop off British author
- Hiker takes stroll between two rivers
- Rose Walker
- Hiker taking walk between two rivers
- Hiker, person walking past river
- Cautionary signal about lake after river rose?
- Risk missing opening in centre of Jarrow for country activist
- Rose maybe better initially turning to right
- Hiker, artist, doctor and queen crossing line
Buddy explains!

The straight part
We know that "Walker/climber" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case walker/climber = rambler.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RAMBLER mean?
RAMBLER noun- A recreational walker, a hiker.
- One who rambles.
- A ranch-style house.