Refurbished a flat and it's deadly (5)
I believe the answer is:
fatal
'it's deadly' is the definition.
('fatal' can be similar in meaning to 'deadly')
'refurbished a flat' is the wordplay.
'refurbished' indicates an anagram.
'a'+'flat'='aflat'
'aflat' anagrammed gives 'FATAL'.
'and' is the link.
(Other definitions for fatal that I've seen before include "very bad for health!" , "Calamitous" , "Disastrous, maybe lethal" , "Mortal" , "Pernicious" .)