Composer minus the lyricist ultimately useless (9)
I believe the answer is:
tunesmith
'composer' is the definition.
(thesaurus)
'minus the lyricist ultimately useless' is the wordplay.
'ultimately' says to take the final letters.
'useless' indicates anagramming the letters.
The last letter of 'lyricist' is 't'.
'minus'+'the'+'t'='minusthet'
'minusthet' is an anagram of 'TUNESMITH'.
(Other definitions for tunesmith that I've seen before include "Melody Maker" , "I produce strains" , "Composer" .)