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' indicates putting letters inside.
'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" .)