Queen Elizabeth follows favourite saint (5)
I believe the answer is:
peter
'saint' is the definition.
(I know that Peter is a saint)
'queen elizabeth follows favourite' is the wordplay.
'queen elizabeth' becomes 'ER' (abbreviation for Elizabeth Regina).
'follows' means one lot of letters go next to another.
'favourite' becomes 'pet' (synonyms).
'er' put after 'pet' is 'PETER'.
(Other definitions for peter that I've seen before include "emperor" , "Disciple" , "Man's name" , "Fellow < safe" , "Leading apostle" .)