Sort of peak Bono & The Edge: ignoring Yoko (4)
I believe the answer is:
brim
'sort of peak' is the definition.
(part of a hat)
'bono the edge ignoring yoko' is the wordplay.
'the edge' becomes 'rim' (rim is a kind of edge).
'ignoring' indicates named letters should be taken away.
'yoko' becomes 'ono' (musician Yoko Ono).
'bono'+'rim'='bonorim'
'bonorim' with 'ono' taken away is 'BRIM'.
(Other definitions for brim that I've seen before include "Upper edge" , "Edge (of cup or hat)" , "Peak (of cap); be very full" , "Cup's lip" , "Lip; part of a hat" .)