Deity takes nothing to be beneficial (4)
I believe the answer is:
good
'beneficial' is the definition.
(synonyms)
'deity takes nothing' is the wordplay.
'deity' becomes 'god' (a deity is a god or divine being).
'takes' means one lot of letters goes inside another.
'nothing' becomes 'O' (O resembles 0).
'god' enclosing 'o' is 'GOOD'.
'to be' is the link.
(Other definitions for good that I've seen before include "(Of child) well-behaved" , "Moral excellence" , "Having desirable qualities" , "Carol character from 1 as of old" , "Virtuous - valid" .)