Greenhouse gas (7)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">greenhouse gas</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 methane that I've seen before include "Greenhouse gas produced by cows" , "Naturally occurring flammable gas" , "Main constituent of natural gas" , "Combustible atmosphere" , "contributor to global warming" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">greenhouse gas</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for carbon dioxide that I've seen before include "Gas produced in breathing" , "Gas for dry ice" , "Gas formed by breathing out" , "gas from exhaust?" , "Gas breathed out" .)