Terrible barney is close (6)
I believe the answer is:
nearby
'is close' is the definition.
('nearby' can be similar in meaning to 'close')
'terrible barney' is the wordplay.
'terrible' is an anagram indicator.
'barney' is an anagram of 'NEARBY'.
(Other definitions for nearby that I've seen before include "[OPPOSITE OF] miles away" , "A short distance away" , "In the vicinity" , "Locally" , "Barney (anag)" .)