Booked as promised (7)
I believe the answer is:
engaged
I believe this is a double definition.
'booked' is the first definition.
(synonyms)
'promised' is the second definition.
(synonyms)
'as' acts as a link.
(Other definitions for engaged that I've seen before include "Not free" , "In use" , "Started fighting" , "looking forward to the match?" , "Affianced" .)