One feeds three queens (7)
I believe the answer is:
caterer
'one feeds' is the definition.
(someone who provides food)
'three queens' is the wordplay.
'three queens' means three replacements for 'queen'.
'queen' becomes 'cat' (a queen is a female cat).
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'cat'+'er'+'er'='CATERER'
(Other definitions for caterer that I've seen before include "Refreshment supplier" , "Food and drink supplier" , "One supplying cheer" , "Someone providing food and service" , "One providing food and service for a party" .)