Forest officer (6)
I believe the answer is:
ranger
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">forest officer</span>' is the definition.<br/ ><span class="explanation-format__explanation">(a ranger might look after a forest)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ranger that I've seen before include "Park official" , "National park officer" , "Rover" , "park-keeper" , "Forest official" .)