Home outside of Tredegar entered by rough trespasser (8)
I believe the answer is:
intruder
'trespasser' is the definition.
(synonyms)
'home outside of tredegar entered by rough' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'outside of' means to remove the middle letters (only letters on the outside of the word).
'entered by' means one lot of letters goes inside another (I've seen this in other clues).
'rough' becomes 'rude' (similar in meaning).
'tredegar' with its centre removed is 'tr'.
'tr' placed around 'rude' is 'truder'.
'in'+'truder'='INTRUDER'
(Other definitions for intruder that I've seen before include "Unwelcome sort" , "Uninvited guest" , "Butter in" , "Person who comes in being neither invited nor wanted" , "One entering unasked" .)