Hike from capital south, about to go outside (5)
I believe the answer is:
raise
'hike' is the definition.
(I know that hike is a kind of raise)
'capital south about to go outside' is the wordplay.
'capital' becomes 'AI' (resembles Ar, which can mean capital or excellent).
'south' becomes 's' (abbreviation).
'about to go' becomes 're' (I've seen this in other clues).
'outside' means one lot of letters goes inside another (some letters go outside others).
'ai'+'s'='ais'
'ais' put within 're' is 'RAISE'.
'from' acts as a link.
(Other definitions for raise that I've seen before include "Bring up a salary increase" , "Lift, elevate" , "Wage increase" , "climb" , "Uplift" .)