Bay window (5)
I believe the answer is:
oriel
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bay window</span>' is the definition.<br/ ><span class="explanation-format__explanation">(oriel is a type of bay window)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for oriel that I've seen before include "place to study at Oxford" , "Window built out from upper floor" , "Overhanging recess (window)" , "Type of window; Oxford college" , "This window projects from upper storey" .)