Crossword Genius

Does editors job first and last? (7)

Ross

I believe the answer is:

subsist

I'm a little stuck... Click here to teach me more about this clue!

'last?' is the definition.
(thesaurus)

'does editors job first' is the wordplay.
I cannot quite understand how this works, but
'first' could be 'ist' (ist resembles 1st) and 'ist' is present in the answer.
The remaining letters 'subs' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'and' acts as a link.

Can you help me to learn more?

(Other definitions for subsist that I've seen before include "Have the necessities for life" , "Eke out a living" , "Get by at minimum level" , "Live at a minimal level" , "Eke out an existence" .)

I've seen this clue in The Sun.
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