Attempt to take in old play (7)
I believe the answer is:
tragedy
'play' is the definition.
(I have seen 'Serious play ' mean 'tragedy' so perhaps 'play' could also mean 'tragedy')
'attempt to take in old' is the wordplay.
'attempt' becomes 'try' (I've seen this before).
'to take in' means one lot of letters goes inside another.
'old' becomes 'aged' ('aged' can be similar in meaning to 'old').
'try' placed around 'aged' is 'TRAGEDY'.
(Other definitions for tragedy that I've seen before include "play by Shakespeare?" , "Play with sad ending" , "Terribly sad thing" , "sad event" , "Play with a gloomy finish" .)