Negligible note with a line (7)
I believe the answer is:
minimal
'negligible' is the definition.
(similar in meaning)
'note with a line' is the wordplay.
'note' becomes 'minim' (type of musical note).
'with' says to put letters next to each other.
'line' becomes 'l' (used when specifying particular lines from a poem).
'minim'+'a'+'l'='MINIMAL'
(Other definitions for minimal that I've seen before include "Token" , "Least possible; negligible" , "Of a smallest amount" , "Very little" , "Of the least possible size" .)