Jam containers (4)
I believe the answer is:
jars
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">jam containers</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for jars that I've seen before include "Jam pots" , "Vessels with a wide mouths" , "Wide-mouthed containers" , "Grates" .)