Overly proper (4)
I believe the answer is:
prim
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">overly proper</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 prim that I've seen before include "Prudish, proper" , "Straitlaced and proper" , "Old-maidish" , "Prudishly disapproving" , "Demure" .)