Yes, mistake occurs after pressure to provide proof of earnings (7)
I believe the answer is:
payslip
'proof of earnings' is the definition.
(record of one's earnings)
'yes mistake occurs after pressure' is the wordplay.
'yes' becomes 'ay'.
'mistake' becomes 'slip' (a slip is a blunder or mistake).
'occurs after' is a charade indicator (letters next to each other).
'pressure' becomes 'p' (abbreviation).
'ay'+'slip'='ayslip'
'ayslip' put after 'p' is 'PAYSLIP'.
'to provide' acts as a link.
(Other definitions for payslip that I've seen before include "Detachable form accompanying cheque" , "Monthly advice for employee" , "Paper to accompany cheque" , "note from employer" , "Capital of Italy" .)