Type of low cloud (7)
I believe the answer is:
stratus
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">type of low cloud</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 stratus that I've seen before include "Source of rain" , "Sheet of low cloud" , "Cloud cover" , "Large dark low cloud" , "Continuous cloud type" .)