Wear down some superhero demands (5)
I believe the answer is:
erode
'wear down' is the definition.
(to erode is to wear down or decay)
'some superhero demands' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'ERODE' can be found hidden inside 'superhero demands'.
(Other definitions for erode that I've seen before include "Wear away with weather" , "Grind down" , "Corrode" , "Eat away" , "'Deteriorate, wear away (5)'" .)