Refurbished a flat - it's deadly (5)
I believe the answer is:
fatal
'deadly' is the definition.
('fatal' can be similar in meaning to 'deadly')
'refurbished a flat' is the wordplay.
'refurbished' is an anagram indicator.
'a'+'flat'='aflat'
'aflat' anagrammed gives 'FATAL'.
'it's' is the link.
(Other definitions for fatal that I've seen before include "Deadly force" , "Calamitous" , "making one late" , "Bringing ruin" , "Disastrous, maybe lethal" .)