Sadly returned envelope of ready money (6)
I believe the answer is:
salary
'money' is the definition.
'sadly returned envelope of ready' is the wordplay.
'sadly' becomes 'alas' (I've seen this before).
'returned' is a reversal indicator.
'envelope of' means to remove the middle letters (the outside letters are the word's envelope).
'ready' with its centre removed is 'ry'.
'alas' backwards is 'sala'.
'sala'+'ry'='SALARY'
(Other definitions for salary that I've seen before include "Fixed regular payment of work" , "that's usually banked" , "Worker's pay" , "Employee's remuneration" , "payment only for non-manual workers" .)