Busy being a bit platitudinous (2,2)
I believe the answer is:
at it
'busy' is the definition.
(I've seen this before)
'a bit platitudinous' is the wordplay.
'a bit' indicates the answer is hidden within the clue (I've seen 'bit of' mean this).
'AT IT' is hidden in the letters of 'platitudinous'.
'being' acts as a link.
(Other definitions for at it that I've seen before include "occupied in a particular way" , "Busy" , "engaged in crime?" , "Active" , "Engaged in something particular" .)