Burrow, rummage (5)
I believe the answer is:
delve
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">burrow</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that burrow is a more specific form of the action delve)</span><br/ ><br/ >'<span class="explanation-format__original">rummage</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for delve that I've seen before include "Look closely (into)" , "Hollow" , "Make painstaking enquiries (into something)" , "Dig - investigate" , "Intensively research (into something)" .)