Deputy doctor (5)
I believe the answer is:
locum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">deputy 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 locum that I've seen before include "Medical temp?" , "Stand-in professional" , "Stand-in, for a doctor say" , "may step into someone else's job" , "He fills in" .)