Composure of bishop, leader of church in a restricted way (7)
I believe the answer is:
balance
'composure' is the definition.
(thesaurus)
'bishop leader of church in a restricted way' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'leader of' says to take the initial letters.
'in' indicates putting letters inside.
'restricted way' becomes 'lane' (as in a lane of traffic).
The first letter of 'church' is 'c'.
'a'+'lane'='alane'
'c' put inside 'alane' is 'alance'.
'b'+'alance'='BALANCE'
'of' is the link.
(Other definitions for balance that I've seen before include "emotional stability" , "Weighing apparatus" , "Equipoise" , "Scale for weighing" , "Surplus" .)