A celebration that spells trouble (3)
I believe the answer is:
ado
'trouble' is the definition.
(both can mean bother or commotion)
'a celebration' is the wordplay.
'celebration' becomes 'do' (I've seen this in other clues).
'a'+'do'='ADO'
'that spells' acts as a link.
(Other definitions for ado that I've seen before include "Hoo-ha" , "Song and dance" , "excitement" , "hoo-hah" , "flapping" .)