Simple and guileless (5)
I believe the answer is:
naive
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">simple and guileless</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for naive that I've seen before include "Innocent or not worldly enough" , "Ingenous, easy to gull" , "Unsophisticated and gullible" , "Unenlightened" , "Lacking worldly experience" .)