Inclination to adopt very English raising agent (9)
I believe the answer is:
leavening
'raising agent' is the definition.
'leavening' can be an answer for 'agent' (I have seen 'Influential agent' mean 'leavening' so perhaps 'agent' could also mean 'leavening'). I am not sure about the 'raising' bit.
'inclination to adopt very english' is the wordplay.
'inclination' becomes 'leaning' (incline can mean to lean).
'to adopt' indicates putting letters inside (inserted letters are taken in or adopted).
'very' becomes 'v' (abbreviation).
'english' becomes 'E' (abbreviation).
'v'+'e'='ve'
'leaning' enclosing 've' is 'LEAVENING'.
Can you help me to learn more?
(Other definitions for leavening that I've seen before include "Making to rise" , "Riser" , "Pervading, causing gradual change" , "Influential agent" , "eg Yeast" .)