Goat is ready to start getting drunk, a debauchee (7)
I believe the answer is:
orgiast
'a debauchee' is the definition.
(both can mean an excessively indulgent person)
'goat is ready to start getting drunk' is the wordplay.
'to start' says to take the initial letters.
'getting drunk' indicates an anagram.
The first letter of 'ready' is 'r'.
'goat'+'is'+'r'='goatisr'
'goatisr' is an anagram of 'ORGIAST'.
(Other definitions for orgiast that I've seen before include "Party animal" , "one taking part in drunken revel" , "Wild reveller" .)