Schumann's opening surprisingly lofty for piano (6)
I believe the answer is:
softly
'for piano' is the definition.
(synonyms)
'schumann's opening surprisingly lofty' is the wordplay.
'opening' indicates taking the first letters.
'surprisingly' is an anagram indicator (a surprising ordering of the letters).
The initial letter of 'schumanns' is 's'.
'lofty' with letters rearranged gives 'oftly'.
's'+'oftly'='SOFTLY'
(Other definitions for softly that I've seen before include "Quietly or gently" , "With a quiet and gentle voice" , "Piano" , "In a yielding manner" , "Lightly, quietly" .)