Where there's smoke (4)
I believe the answer is:
flue
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">where there's smoke</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 flue that I've seen before include "Chimney shaft" , "Passage for air" , "Chimney channel" , "Smoke-duct in a chimney" , "Fuel (anag.)" .)