State welcome includes a whiskey — first class! (6)
I believe the answer is:
hawaii
'state' is the definition.
(Hawaii is a state of the USA)
'welcome includes a whiskey first class' is the wordplay.
'welcome' becomes 'hi' (both are greetings).
'includes' means one lot of letters goes inside another.
'whiskey' becomes 'W' (alpha bravo charlie delta ...).
'first class' becomes 'ai' (A1 - top quality).
'a'+'w'+'ai'='awai'
'hi' going around 'awai' is 'HAWAII'.
(Other definitions for hawaii that I've seen before include "Honolulu's state" , "It became a US territory in 1900" , "State capital is Honolulu" , "Birthplace of the 44th US president" , "holiday island" .)