Trattoria topping (5)
I believe the answer is:
pesto
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">trattoria topping</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 pesto that I've seen before include "Sauce of basil, pine nuts and garlic" , "Saucy work" , "Ligurian food" , "Pasta sauce variety" , "Pasta sauce based on basil" .)