Foiled - the trespassers? (6)
I believe the answer is:
fenced
'foiled the trespassers?' is the definition.
The answer and definition can be both to do with contact as well as being past participle verbs.
Perhaps you can see a link between them that I don't see?
This is all the clue.
Can you help me to learn more?
(Other definitions for fenced that I've seen before include "Enclosed with a palisade" , "protected by barrier" , "Got hold of hot stuff" , "Enclosed with palings" , "Enclosed by hedges or engaged in swordplay" .)