Fruits of the oak (6)
I believe the answer is:
acorns
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fruits of the oak</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 acorns that I've seen before include "nuts" , "Potential oaks?" , "'From little . . . . . . mighty oaks do grow'" , "'Great oaks from little ...... grow'" , "From which great oak trees grow" .)