Increase in price for walking tour (4)
I believe the answer is:
hike
This clue is a double definition.
'increase in price' is the first definition.
(as in a price hike)
'walking tour' is the second definition.
(I've seen this before)
'for' is the link.
(Other definitions for hike that I've seen before include "Walking tour" , "Long walk; big price rise" , "Tramp" , "Long, hard walk" , "Long march; increase" .)