They were accused of 'spying' for a foreign government.
a 'spy' camera/plane [=a camera/plane used for spying]
a 'spy' novel/thriller [=a novel/thriller about spies]
(..) - It didn't name you. But the way you've been... - acting, I just assumed... - I don't believe you. It was Barrow who sent you to spy on me, wasn't it? Wasn't it?! Oh, God. Oh, God. What can I do to help? Nothing. (..)2014 TvShow: The Knick Title: The Golden Lotus Season: 1 Episode 9
(..) - Nobody sent me. - Was it Robertson? - Miss Robertson? - Her father. Did that son of a bitch send you to spy on me? John, did something happen to you last night? You look terrible. - When did you last eat? - I'm not hungry. (..)2014 TvShow: The Knick Title: The Golden Lotus Season: 1 Episode 9