A club to back Rhode Island slaughterhouse (8)
I believe the answer is:
abattoir
'slaughterhouse' is the definition.
(synonyms)
'a club to back rhode island' is the wordplay.
'club' becomes 'bat' (as in sporting equipment).
'back' shows that the letters should be reversed in order.
'rhode island' becomes 'ri' (US postal abbreviation).
'ri' written backwards gives 'ir'.
'a'+'bat'+'to'+'ir'='ABATTOIR'
(Other definitions for abattoir that I've seen before include "Animal slaughter-house" , "it makes a killing" , "I tar boat (anag)" , "[EASY MEAT] half-cut seen here?" , "scene of slaughter" .)