Irish girl playing cello with two leading Englishmen (7)
I believe the answer is:
colleen
'irish girl' is the definition.
(common Irish name)
'playing cello with two leading englishmen' is the wordplay.
'playing' indicates anagramming the letters.
'with two leading englishmen' becomes 'en' (I am not sure about this - if you are sure you should believe this answer much more).
'cello' with letters rearranged gives 'colle'.
'colle'+'en'='COLLEEN'
(Other definitions for colleen that I've seen before include "Irish miss" , "Young Irish woman" , "Irish girl, English version" , "Irish lass" , "Find Irish girl in cell one" .)