Worked with us, taking notes (4)
I believe the answer is:
used
'worked with' is the definition.
(I've seen this in another clue)
'us taking notes' is the wordplay.
'taking' is a charade indicator (letters next to each other).
'notes' becomes 'ed' ().
'us'+'ed'='USED'
(Other definitions for used that I've seen before include "Pre-loved" , "Dog-eared" , "Was treating" , "Sued, having been employed" , "Manipulated American editor" .)