Score's steady, so sent out afresh (9)
I believe the answer is:
sostenuto
'score's steady' is the definition.
(musical term meaning to play in a steady manner)
'so sent out afresh' is the wordplay.
'afresh' indicates anagramming the letters.
'sent'+'out'='sentout'
'sentout' is an anagram of 'stenuto'.
'so'+'stenuto'='SOSTENUTO'
(Other definitions for sostenuto that I've seen before include "In this way" , "smoothly, not letting up" , "musical movement" .)