Single: piece of vinyl, nostalgic looking back (4)
I believe the answer is:
only
'single' is the definition.
(similar in meaning)
'piece of vinyl nostalgic looking back' is the wordplay.
'piece of' indicates the answer is hidden within the clue.
'looking back' is a reversal indicator.
'ylno' can be found hidden inside 'vinyl nostalgic'.
'ylno' back-to-front is 'ONLY'.
(Other definitions for only that I've seen before include "Single, solitary" , "See 6" , "Simply" , "Siblingless (child)" , "Except that; single" .)