Sitcom installment (7)
I believe the answer is:
episode
'sitcom installment' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for episode that I've seen before include "One part of a series" , "Incident forming part of a sequence" , "One instalment of a series" , "Musical passage" , "Event or series of events in a story" .)