Walk the first incline (5)
I believe the answer is:
tramp
'walk' is the definition.
(tramp is a kind of walk)
'the first incline' is the wordplay.
'first' says to take the initial letters.
'incline' becomes 'ramp' ('ramp' can be a synonym of 'incline').
The initial letter of 'the' is 't'.
't'+'ramp'='TRAMP'
(Other definitions for tramp that I've seen before include "Down-and-out" , "Vagrant, hobo" , "March heavily like hobo" , "Disreputable wanderer" , "The man on the street?" .)