Toddlers kept engaged by this dramatic series? (9)
I believe the answer is:
playgroup
'toddlers kept engaged by this' is the definition.
(place for young children to play)
'dramatic series?' is the wordplay.
'dramatic' becomes 'play' (a play is a drama).
'series?' becomes 'group' (series is a kind of group).
'play'+'group'='PLAYGROUP'
(Other definitions for playgroup that I've seen before include "Gathering of the very young" , "Where infants may be" , "meeting for parents and children" .)