Covert (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">covert</span>' is the definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for secret that I've seen before include "Private, or something private" , "Not generally known" , "Hidden, private" , "Not known by others" , "Private, covert" .)
(Other definitions for ops that I've seen before include "Surgical procedures (abbr)" , "Operations (colloq.)" , "jobs in the theatre" , "facelifts, perhaps" , "medical procedures" .)