Navy doctor (7)
I believe the answer is:
surgeon
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">navy doctor</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for surgeon that I've seen before include "one performing in the theatre" , "Theatre operator" , "Physician" , "Operating medic" , "Go, nurse for the operator" .)