Engage in drama - one scene (4,1,4)
I believe the answer is:
play a part
'engage' is the definition.
Although both the answer and definition are verbs in their base form, I don't see how they can define each other.
'drama one scene' is the wordplay.
'drama' becomes 'play' (synonyms).
'one scene' becomes 'apart' (I can't explain this - if you can you should give a lot more credence to this answer).
'play'+'apart'='PLAY A PART'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for play a part that I've seen before include "Contribute" , "Be instrumental (in an activity)" .)