Possible Clues:

• Far-too-memorable song
• Tune that really catches on
• Tune you just can't get out of your head
• European member admits line cocked up in memorable song
• Melody that overstays its welcome
• More war-wounded, number hard to forget?
• Tune that's tough to get out of your head
• Song you can't get out of your head
• Song that's hard to get out of your head
• The 1975 hit 'Can't Get It Out of My Head' would be an appropriate one