Shadowed (6)
I believe the answer is:
tailed
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">shadowed</span>' is the definition.<br/ ><span class="explanation-format__explanation">(tailing is a kind of shadowing)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tailed that I've seen before include "Dogged" , "Followed (suspect)" , "Followed informally in detail" , "Followed, tracked" , "Secretly followed" .)