Singer Campbell (4)
I believe the answer is:
glen
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">singer campbell</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for glen that I've seen before include "Narrow valley with a stream" , "Narrow, deep mountain valley" , "Valley, dale" , "Narrow secluded valley in mountains" , "Narrow Scots valley" .)