Trespass, having ruined layout around junction (7)
I believe the answer is:
intrude
'trespass' is the definition.
(synonyms)
'ruined layout around junction' is the wordplay.
'layout' indicates anagramming the letters (an alternative layout of the letters).
'around' indicates putting letters inside.
'junction' becomes 't'.
'ruined' anagrammed gives 'inrude'.
'inrude' enclosing 't' is 'INTRUDE'.
'having' acts as a link.
(Other definitions for intrude that I've seen before include "Pry" , "meddle" , "Push in where not wanted" , "Come in without invitation" , "Come in when not wanted" .)