Old relative to initial sum bestowed (5)
I believe the answer is:
grant
'sum bestowed' is the definition.
I can't tell whether this defines the answer.
'old relative to initial' is the wordplay.
'old relative' becomes 'gran' (grandmother).
'initial' indicates taking the first letters.
The first letter of 'to' is 't'.
'gran'+'t'='GRANT'
Can you help me to learn more?
(Other definitions for grant that I've seen before include "yield" , "Give or allow as a privilege" , "Greek, a soldier" , "Allow (something)" , "Cary, Duncan or Ulysses S?" .)