Slips into (4)
I believe the answer is:
dons
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">slips into</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 dons that I've seen before include "Assumes" , "Academics" , "Puts on -- lecturers" , "University teachers - Mafia bosses" , "British university teachers and Spanish noblemen" .)