Cambridge crew losing first classic (5)
I believe the answer is:
oldie
'classic' is the definition.
(eg a classic song)
'cambridge crew losing first' is the wordplay.
'cambridge crew' becomes 'Goldie' (reserve rowing crew of Cambridge University).
'losing first' means to remove the first letter.
'goldie' with its first letter taken off is 'OLDIE'.
(Other definitions for oldie that I've seen before include "classic film perhaps" , "Senior citizen" , "one who is past it?" , "The --, UK magazine" , "Elderly person" .)