Yorkshire valleys (5)
I believe the answer is:
dales
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">yorkshire valleys</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 dales that I've seen before include "Leads into poetic valleys" , "Open river valleys in hilly areas" , "Yorkshire valleys" , "(North England) valleys" .)