State of liquor knocked back by queen (5)
I believe the answer is:
niger
'state' is the definition.
(I know that Niger is a African country)
'liquor knocked back by queen' is the wordplay.
'liquor' becomes 'gin' (gin is a kind of liquor).
'knocked back' says the letters should be written in reverse.
'by' means one lot of letters go next to another.
'queen' becomes 'ER' (short for Elizabeth Regina ie Queen Elizabeth).
'gin' in reverse letter order is 'nig'.
'nig'+'er'='NIGER'
'of' is the link.
(Other definitions for niger that I've seen before include "Major West African river" , "Landlocked W African republic" , "West African republic" , "Country in interior of N Africa, capital Niarney" , "one flowing through Mali" .)