Cool iron leading to oddly random blaze (7)
I believe the answer is:
inferno
'blaze' is the definition.
(thesaurus)
'cool iron leading to oddly random' is the wordplay.
'cool' becomes 'in' (I've seen this in other clues**).
'iron' becomes 'fe' (Fe is the chemical symbol for iron).
'leading to' means one lot of letters go next to another (some letters go before or lead others).
'oddly' indicates alternate letters.
The alternate letters of 'random' are 'rno'.
'in'+'fe'+'rno'='INFERNO'
(Other definitions for inferno that I've seen before include "A raging fire as in hell - ask Dante" , "blazer?" , "Nine Circles here" , "Large dangerous fire" , "Where Satan lives and sinners go" .)