Specials end up supporting Arctic Monkeys primarily? Flipping nonsense! (7)
I believe the answer is:
madness
'nonsense' is the definition.
(thesaurus)
'specials end up supporting arctic monkeys primarily? flipping' is the wordplay.
'specials' becomes 'ss' (an abbreviation for special written twice).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'primarily?' suggests taking the first letters (I've seen 'primarily' mean this).
'flipping' says the letters should be written in reverse.
The initial letters of 'arctic monkeys' is 'am'.
'ss'+'end'='ssend'
'ssend' reversed gives 'dness'.
'am' written backwards gives 'ma'.
'dness' put after 'ma' is 'MADNESS'.
(Other definitions for madness that I've seen before include "Dementia" , "Lunacy - ska/pop band" , "Group" , "great anger" , "Folly" .)