Job, say, that is one with better earnings (6)
I believe the answer is:
bookie
'job' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'that is one with better earnings' is the wordplay.
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'one with' means one lot of letters go next to another.
'better earnings' becomes 'book' (I can't justify this - if you can you should believe this answer much more).
'ie' after 'book' is 'BOOKIE'.
'say' is the link.
Can you help me to learn more?
(Other definitions for bookie that I've seen before include "One taking bets for horse races" , "Betting organiser" , "Turf accountant" .)