Bad thing to celebrate endlessly (3)
I believe the answer is:
sin
'bad thing' is the definition.
'sin' can be an answer for 'bad' (thesaurus). I am not sure about the 'thing' bit.
'celebrate endlessly' is the wordplay.
'celebrate' becomes 'sing' (as in to sing someone's praises).
'endlessly' means to remove the last letter.
'sing' with its last letter removed is 'SIN'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for sin that I've seen before include "Immoral action" , "Fall from grace" , "Serious offence" , "Breach of moral code" , "Immoral act" .)