One serves three queens (7)
I believe the answer is:
caterer
'one' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'three queens' is the wordplay.
'three queens' means three replacements for 'queen'.
'queen' becomes 'cat' (a queen is a female cat).
'queen' becomes 'ER' (short for Elizabeth Regina ie Queen Elizabeth).
'queen' becomes 'ER' (short for Elizabeth Regina ie Queen Elizabeth).
'cat'+'er'+'er'='CATERER'
'serves' acts as a link.
Can you help me to learn more?
(Other definitions for caterer that I've seen before include "Food and drink supplier" , "Terrace (anag.)" , "Provider of food and drinks" , "One providing food and drink" , "Refreshment supplier" .)