Initially some plays only occasionally featured such burlesques (6)
I believe the answer is:
spoofs
'burlesques' is the definition.
('spoof' can be a synonym of 'burlesque')
'initially some plays only occasionally featured such' is the wordplay.
'initially' indicates taking the first letters.
The initial letters of 'some plays only occasionally featured such' is 'SPOOFS'.
(Other definitions for spoofs that I've seen before include "Tricks" , "Lampoons" , "Hoaxes or humorous imitations" , "Satirical imitations, parodies" , "Slangy hoaxes or imitations" .)