Crown representative up north in ravine near choppy lake (8,7)
I believe the answer is:
governor general
'crown representative' is the definition.
'up north in ravine near choppy lake' is the wordplay.
'up' becomes 'over'.
'north' becomes 'n' ('N' can be a synonym of 'north').
'in' indicates putting letters inside.
'ravine' becomes 'gorge' (gorge is a kind of ravine).
'near choppy lake' becomes 'neral' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'over'+'n'='overn'
'overn' placed within 'gorge' is 'governorge'.
'governorge'+'neral'='GOVERNOR-GENERAL'
(Other definitions for governor general that I've seen before include "acting head of state" , "Commonwealth official" .)