Took on work with provider of talks after a day (7)
I believe the answer is:
adopted
'took on' is the definition.
('adopt' can be a synonym of 'take on')
'work with provider of talks after a day' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'with' is a charade indicator (letters next to each other).
'provider of talks' becomes 'TED' (as in the TED Talks scheme).
'after' is a charade indicator (letters next to each other).
'day' becomes 'd' (abbreviation for day).
'op' put next to 'ted' is 'opted'.
'a'+'d'='ad'
'opted' put after 'ad' is 'ADOPTED'.
(Other definitions for adopted that I've seen before include "Took into one's family" , "Like issue raised by others" , "Espoused" , "Assumed (an attitude)" , "Fostered - assumed" .)