Mediaeval production that might baffle an audience today (7,4)
I believe the answer is:
mystery play
'might baffle an audience today' is the definition.
I can't tell whether this defines the answer.
'mediaeval production' is the wordplay.
'mediaeval' becomes 'mystery' (I am not sure about this - if you are sure you should believe this answer much more).
'production' becomes 'play' (I have seen 'Theatrical production' mean 'play' so perhaps 'production' could also mean 'play').
'mystery'+'play'='MYSTERY PLAY'
'that' acts as a link.
Can you help me to learn more?
(Other definitions for mystery play that I've seen before include "Medieval production based on biblical characters" , "Medieval religious enactment" , "Medieval entertainment" .)