Abba song in can following number one? (8)
I believe the answer is:
waterloo
'abba song' is the definition.
(Waterloo is a song by ABBA)
'can following number one?' is the wordplay.
'can' becomes 'loo' (loo is a kind of can).
'following' is a charade indicator (letters next to each other).
'number one?' becomes 'water' (both can euphemistically mean urine).
'loo' put after 'water' is 'WATERLOO'.
'in' is the link.
(Other definitions for waterloo that I've seen before include "song" , "Battle; Abba hit" , "Where Napoleon met his final defeat" , "Napoleon's final battle" , "London railway terminus" .)