Musical foursome going up or down (4)
I believe the answer is:
abba
This might be a double definition.
'musical foursome' is the first definition.
(Swedish pop band)
'up or down' is the second definition.
'going' is the link.
This may not be correct. It may belong to one of the definitions.
Can you help me to learn more?
(Other definitions for abba that I've seen before include "famous pop group" , "Old group" , "Group - father" , "rhymes in Petrarchan sonnet" , "camel-hair coat" .)