Open pie (4)
I believe the answer is:
flan
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">open pie</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 flan that I've seen before include "Open tart with a sweet or savoury filling" , "Quiche" , "Baked dish filled with fruit or custard" , "Open pastry filled with savouries, fruit or custard" , "pudding!" .)