Pay a casual visit (4,2)
I believe the answer is:
drop in
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pay a casual visit</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for drop in that I've seen before include "Make a casual visit" , "Pay casual call or visit" , "Visit casually" , "home visit" , "Pay a casual visit unannounced" .)