Seem to be a very soft listener (6)
I believe the answer is:
appear
'seem to be' is the definition.
(I've seen this before)
'a very soft listener' is the wordplay.
'very soft' becomes 'pp' (musical abbreviation for pianissimo).
'listener' becomes 'ear' (body part which hears or listens).
'a'+'pp'+'ear'='APPEAR'
(Other definitions for appear that I've seen before include "Come into sight, materialise" , "Seem or materialise" , "Become visible or seem" , "Become visible like ghost" , "Develop" .)