Experienced person (3,4)
I believe the answer is:
old hand
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">experienced person</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 old hand that I've seen before include "Experienced practitioner" , "One that's experienced" , "Person with a lot of experience" , "mediaeval script" , "master" .)