Basil and pine nut sauce (5)
I believe the answer is:
pesto
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">basil and pine nut sauce</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</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, etc" , "Saucy work" , "Sauce made of basil and cheese" , "Basil and pine nut sauce" , "A sauce served with pasta" .)