Opening some port, Nigel reflected (5)
I believe the answer is:
intro
'opening' is the definition.
(short for introduction)
'some port nigel reflected' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'reflected' says the letters should be written in reverse.
'ortni' is hidden within 'port nigel'.
'ortni' written backwards gives 'INTRO'.
(Other definitions for intro that I've seen before include "portion of song" , "this may get one started" , "Opening notes" , "Jazz piece" , "Opening passage (abbr)" .)