After tax returns, collapse several times (7)
I believe the answer is:
tenfold
'several times' is the definition.
(multiplied by ten)
'after tax returns collapse' is the wordplay.
'after tax' becomes 'net' (I've seen this before).
'returns' shows that the letters should be reversed in order.
'collapse' becomes 'fold' (as in a business folding).
'net' written backwards gives 'ten'.
'ten'+'fold'='TENFOLD'
(Other definitions for tenfold that I've seen before include "(Multiplied) by putting 0 on end" , "x10" , "several times" , "An order of magnitude as much" , "(Increased) by an order of magnitude" .)