Cool about 'Great Fire' out of control (11)
I believe the answer is:
refrigerate
'cool' is the definition.
(refrigerating is a kind of cooling)
'about great fire out of control' is the wordplay.
'about' becomes 're' (regarding**).
'out of control' indicates anagramming the letters.
'great'+'fire'='greatfire'
'greatfire' is an anagram of 'frigerate'.
're'+'frigerate'='REFRIGERATE'
(Other definitions for refrigerate that I've seen before include "Keep (food or drink) cold" , "Cool!" , "Provide cooling" , "Freeze" , "Chill" .)