Look furtively (4)
I believe the answer is:
peep
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">look furtively</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 peep that I've seen before include "Look slyly" , "Chirp" , "Sly look (palindrome)" , "Peek" , "Look furtively (either way)" .)