Participate in English period (6)
I believe the answer is:
engage
'participate in' is the definition.
(thesaurus)
'english period' is the wordplay.
'english' becomes 'eng' (abbreviation).
'period' becomes 'age' (age is a kind of period).
'eng'+'age'='ENGAGE'
(Other definitions for engage that I've seen before include "attack" , "Hold" , "Take on - reserve - promise" , "Employ or captivate" , "Recruit" .)