Singer requires brasses from time to time (4)
I believe the answer is:
bass
'singer' is the definition.
(I know that bass is a type of singer)
'brasses from time to time' is the wordplay.
'from time to time' means one should take alternating letters (letters removed on a regular basis).
The alternate letters of 'brasses' are 'BASS'.
'requires' is the link.
(Other definitions for bass that I've seen before include "Low singer" , "deep in the sound" , "Performer" , "Fish, guitar" , "Large fish - singer" .)