Increase walk (4)
I believe the answer is:
hike
This clue is a double definition.
'increase' is the first definition.
(I know that hike is a type of increase)
'walk' is the second definition.
(I know that hike is a type of walk)
(Other definitions for hike that I've seen before include "Go walking with equipment" , "physical exercise" , "(Price) increase; walk" , "Travel by Shank's Mare" , "Long march; increase" .)