Escort's offering (3)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">escort's offering</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for arm that I've seen before include "Shoulder-to-wrist member" , "Supply weapons" , "Prime" , "ready for war" , "strip of land?" .)