Rubbish outside place, last bit of festive decoration (7)
I believe the answer is:
rosette
'decoration' is the definition.
(I know that rosette is a type of adornment)
'rubbish outside place last bit of festive' is the wordplay.
'rubbish' becomes 'rot' (both can mean nonsense).
'outside' means one lot of letters goes inside another.
'place' becomes 'set' (synonyms).
'last bit of' says to take the final letters.
The final letter of 'festive' is 'e'.
'rot' placed around 'set' is 'rosett'.
'rosett'+'e'='ROSETTE'
(Other definitions for rosette that I've seen before include "Ribbon prize or badge" , "Cockade" , "Type of award" , "Prize; favour" , "Pattern" .)