Pays no attention to singer, worried about nothing (7)
I believe the answer is:
ignores
'pays no attention to' is the definition.
(I've seen this before)
'singer worried about nothing' is the wordplay.
'worried' indicates an anagram.
'about' is an insertion indicator.
'nothing' becomes 'o' (looks like zero - 0).
'singer' anagrammed gives 'ignres'.
'ignres' going around 'o' is 'IGNORES'.
(Other definitions for ignores that I've seen before include "cuts" , "Pays no attention to" , "Shrugs off" , "Passes over" , "Gives the cold shoulder" .)