Rowdy mob, one overwhelmed by drink, in a state (8)
I believe the answer is:
colombia
'a state' is the definition.
(Colombia is an example)
'rowdy mob one overwhelmed by drink' is the wordplay.
'rowdy' is an anagram indicator.
'one' becomes 'i' (Roman numeral).
'overwhelmed by' indicates putting letters inside (inserted letters get absorbed or overwhelmed).
'drink' becomes 'cola' (cola is a type of drink).
'mob'+'i'='mobi'
'mobi' with letters rearranged gives 'ombi'.
'ombi' placed within 'cola' is 'COLOMBIA'.
'in' acts as a link.
(Other definitions for colombia that I've seen before include "S American state" , "Bogot++ is its capital" , "Coffee-exporting South American country" , "South American Republic" , "Northwestern republic in South America" .)