Stupidly compose any line (7)
I believe the answer is:
inanely
'stupidly' is the definition.
(I've seen this before)
'compose any line' is the wordplay.
'compose' indicates anagramming the letters.
'any'+'line'='anyline'
'anyline' with letters rearranged gives 'INANELY'.
(Other definitions for inanely that I've seen before include "In a fatuous manner" , "Vapidly" , "Senselessly" , "in a daft way" , "Stupidly" .)