Permit everything to old wife (5)
I believe the answer is:
allow
'permit' is the definition.
(I know that permit can be written as allow)
'everything to old wife' is the wordplay.
'everything' becomes 'all' (all things).
'to old' becomes 'o' (abbreviation).
'wife' becomes 'w' (abbreviation).
'all'+'o'+'w'='ALLOW'
(Other definitions for allow that I've seen before include "Permit or acknowledge" , "brook" , "Sanction" , "Tolerate" , "Grant" .)