Northern stream (4)
I believe the answer is:
beck
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">northern stream</span>' is the definition.<br/ ><span class="explanation-format__explanation">(Northern English dialect term for a stream)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for beck that I've seen before include "burn" , "Poetic gesture" , "The Yardbirds' guitarist, Jeff" , "Stream (N. England)" , "Fast stream; goes with call" .)