Left writer fitting in second episode (10)
I believe the answer is:
instalment
'episode' is the definition.
('instalment' can be a synonym of 'episode')
'left writer fitting in second' is the wordplay.
'left' becomes 'l' (common abbreviation).
'writer' becomes 'me' (the person who is writing these clues).
'fitting in' means one lot of letters goes inside another.
'second' becomes 'instant' ('instant' can be a synonym of 'second'**).
'l'+'me'='lme'
'lme' inserted inside 'instant' is 'INSTALMENT'.
(Other definitions for instalment that I've seen before include "episode" , "Chapter" , "part of serial" , "Payment of part of debt" , "One of a series of partial payments" .)