... smashing piano (5)
I believe the answer is:
grand
This clue is a double definition.
'smashing' is the first definition.
(I've seen this in another clue)
'piano' is the second definition.
(I know that grand is a type of piano)
(Other definitions for grand that I've seen before include "PS1000 (sl.)" , "Designed to impress" , "Magnificent, imposing" , "One thousand pounds" , "Type of piano" .)