A flat can lead to such an accident (5)
I believe the answer is:
fatal
'such an accident' is the definition.
'fatal' can be an answer for 'accident' (fatal accident is a kind of accident). I'm not certain of the 'such an' bit.
'a flat can' is the wordplay.
'can' indicates anagramming the letters (I've seen 'canned' mean this (canned can mean drunk)).
'a'+'flat'='aflat'
'aflat' is an anagram of 'FATAL'.
'lead to' is the link.
Can you help me to learn more?
(Other definitions for fatal that I've seen before include "Causing death, say accident" , "very bad for health!" , "Bringing death" , "Disastrous, maybe lethal" , "Deadly force" .)