Enter property unlawfully (8)
I believe the answer is:
trespass
'enter property unlawfully' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for trespass that I've seen before include "Transgress" , "Illegally entering" , "Enter land without permission" , "Enter someone's property unlawfully" , "Enter another's property without permission" .)