Crash softly echoed (5)
I believe the answer is:
prang
'crash' is the definition.
(I've seen this before)
'softly echoed' is the wordplay.
'softly' becomes 'p'.
'echoed' becomes 'rang' ('ring' can be a synonym of 'echo').
'p'+'rang'='PRANG'
(Other definitions for prang that I've seen before include "nasty collision" , "damage" , "Crash (a motor vehicle)" , "Crash (informal)" , "Possible argument with van" .)