Cel material (7)
I believe the answer is:
acetate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cel material</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 acetate that I've seen before include "film on overhead projector" , "Visual aid" , "Recording" , "Transparency; textile fibre" , "Sort of fabric" .)