Consent to reduce meagre earnings (5)
I believe the answer is:
agree
'consent to' is the definition.
(agreeing is a kind of consenting to)
'reduce meagre earnings' is the wordplay.
'reduce' says the answer is hidden in the clue (I've seen 'reduced' mean this (reducing the letters in the clue shows the answer)).
'AGREE' is hidden within 'meagre earnings'.
(Other definitions for agree that I've seen before include "Consent required" , "Have the same opinion" , "Be of one mind" , "concede" , "suit" .)