"Money, Money, Money" group (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">money money money group</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for abba that I've seen before include "Group winning the 1974 Eurovision Song Contest in Brighton" , "striped coat?" , "Swedish artists" , "Coptic bishop's title; Swedish pop group" , "Enclosed rhyme" .)