Permit old wife to pursue everything (5)
I believe the answer is:
allow
'permit' is the definition.
(I know that permit can be written as allow)
'old wife to pursue everything' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'wife' becomes 'w' (abbreviation).
'to pursue' is a charade indicator (letters next to each other).
'everything' becomes 'all' (all things).
'o'+'w'='ow'
'ow' put after 'all' is 'ALLOW'.
(Other definitions for allow that I've seen before include "Permit or concede" , "OK" , "praise no more" , "Tolerate" , "brook" .)