Busy planning to marry (7)
I believe the answer is:
engaged
This clue is a double definition.
'busy' is the first definition.
(I know that busy can be written as engaged)
'planning to marry' is the second definition.
(I've seen this in another clue)
(Other definitions for engaged that I've seen before include "preparing for the match?" , "Busy - fiancee" , "looking forward to the match?" , "Started to fight" , "Employed - to be married? (7)" .)