Rhetoric about priest's leaning (7)
I believe the answer is:
reliant
'leaning' is the definition.
(relying or leaning on others)
'rhetoric about priest's' is the wordplay.
'rhetoric' becomes 'rant' (rant is a kind of rhetoric).
'about' means one lot of letters goes inside another.
'priest' becomes 'eli' (biblical figure).
'rant' enclosing 'eli' is 'RELIANT'.
(Other definitions for reliant that I've seen before include "Robin was one < in need of support" , "Depending (on) - a three-wheeled car" , "Depending (on something)" , "Trusting" , "Depending on another for support" .)