Wall map marker (4)
I believe the answer is:
tack
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wall map marker</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 tack that I've seen before include "Alter course - riding gear" , "Food; nail" , "Staple - food" , "Small nail; sail (boat) against the wind" , "Type of nail" .)