Philosopher David (4)
I believe the answer is:
hume
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">philosopher david</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 hume that I've seen before include "2 [PHILOSOPHER]" , "Scottish philosopher" , "Nobel laureate" , "David ---, philosopher; Basil ---, late Cardinal" .)