Tea drunk by queen in Royal Gala, say (5)
I believe the answer is:
eater
'royal gala say' is the definition.
(I know that Royal Gala is a type of eater)
'tea drunk by queen' is the wordplay.
'drunk' is an anagram indicator.
'by' says to put letters next to each other.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'tea' anagrammed gives 'eat'.
'eat'+'er'='EATER'
'in' is the link.
(Other definitions for eater that I've seen before include "Type of apple" , "diner" , "Consumer of food" , "Consumer at table" , "Person taking course" .)