Gable is part of a roof; you can have a gableD roof though (that folks is from my Construction lectures some few years ago - something that was beaten in to me!)
Captain2, your comment allows me to mention something that I've wanted to mention for some time. Are we seeing more and more clues that appear to be written by setters who are - shall we say - less than precise in their work? And clues are becoming increasingly obscure? Or is it just me who's losing my grip?