Initial section brought back in a fortnight (5)
I believe the answer is:
intro
'initial section' is the definition.
'intro' can be an answer for 'section' (I have seen 'Preliminary section ' mean 'intro' so perhaps 'section' could also mean 'intro'). I'm not sure about the 'initial' bit.
'back in a fortnight' is the wordplay.
'back' says the letters should be written in reverse.
'in' says the answer is hidden in the clue.
'ortni' is hidden within 'fortnight'.
'ortni' written backwards gives 'INTRO'.
'brought' is the link.
Can you help me to learn more?
(Other definitions for intro that I've seen before include "preface" , "Beginning passage" , "First notes" , "First part of a news story (abbr)" , "Lead-in" .)