Joyous time before opening of lamentable ceremony (7)
I believe the answer is:
funeral
'ceremony' is the definition.
(funeral is a kind of ceremony)
'joyous time before opening of lamentable' is the wordplay.
'joyous' becomes 'fun' (I can't explain this - if you can you should give a lot more credence to this answer).
'time' becomes 'era' (an era is a period of time).
'before' means one lot of letters go next to another.
'opening of' suggests taking the first letters.
The initial letter of 'lamentable' is 'l'.
'fun'+'era'+'l'='FUNERAL'
Can you help me to learn more?
(Other definitions for funeral that I've seen before include "Burial ceremony" , "Burial rite" , "Sepulture" , "Burial service" , "Ceremony at disposal of dead" .)