Queen, perhaps, at home with a large Catholic leader (8)
I believe the answer is:
cardinal
'catholic leader' is the definition.
'cardinal' can be an answer for 'leader' (cardinal is a kind of leader). I am not sure about the 'catholic' bit.
'queen perhaps at home with a large' is the wordplay.
'queen perhaps' becomes 'card' (queen is a kind of card).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'with' means one lot of letters go next to another.
'large' becomes 'L' (eg in clothes sizes).
'card'+'in'+'a'+'l'='CARDINAL'
Can you help me to learn more?
(Other definitions for cardinal that I've seen before include "Primary - colour" , "Prince of the Roman Catholic Church" , "Counsellor to the Pope" , "Essential - churchman - songbird" , "Possibly one" .)