Leaderless coppers seizing throne in Vatican City? (7)
I believe the answer is:
enclave
'vatican city?' is the definition.
(the Vatican is an enclave of Italy)
'leaderless coppers seizing throne' is the wordplay.
'leaderless' means to remove the first letter.
'coppers' becomes 'pence' (coppers can mean copper coins).
'seizing' indicates putting letters inside (inserted letters are seized).
'throne' becomes 'lav' (both can informally mean toilet).
'pence' with its initial letter removed is 'ence'.
'ence' going around 'lav' is 'ENCLAVE'.
'in' is the link.
(Other definitions for enclave that I've seen before include "Area enclosed within a foreign territory" , "Land wholly within foreign territory" , "Part of country surrounded by foreign territory" , "Vatican for example" , "Region wholly within another" .)