Eastwood entertains English customer (6)
I believe the answer is:
client
'customer' is the definition.
(synonyms)
'eastwood entertains english' is the wordplay.
'eastwood' becomes 'clint' (I've seen this in another clue).
'entertains' means one lot of letters goes inside another.
'english' becomes 'E' (abbreviation).
'clint' placed around 'e' is 'CLIENT'.
(Other definitions for client that I've seen before include "Employer of professional" , "person lawyer represents" , "Dependant, hanger-on" , "Eg, lawyer's customer" , "Computer program" .)