Old cigar — it’s unusually immoderate (9)
I believe the answer is:
orgiastic
'immoderate' is the definition.
(both can mean excessive or wild)
'old cigar it's unusually' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'unusually' is an anagram indicator.
'cigar'+'its'='cigarits'
'cigarits' anagrammed gives 'rgiastic'.
'o'+'rgiastic'='ORGIASTIC'
(Other definitions for orgiastic that I've seen before include "Debauched" , "become overindulgent" , "Licentious" .)