Close observation (12)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">close observation</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 surveillance that I've seen before include "Covert observation" , "Close observation" , "Watch" .)
(Other definitions for watch that I've seen before include "See 21" , "Observe - guard" , "period of duty" , "Timepiece - look out" , "Keep an eye on - timepiece" .)