Dirges using feeble notes, oddly (7)
I believe the answer is:
laments
'dirges' is the definition.
('lament' can be a synonym of 'dirge')
'feeble notes oddly' is the wordplay.
'feeble' becomes 'lame' ('lame' can be a synonym of 'feeble').
'oddly' indicates alternate letters.
The alternate letters of 'notes' are 'nts'.
'lame'+'nts'='LAMENTS'
'using' is the link.
(Other definitions for laments that I've seen before include "Feels regret" , "Bewails" , "Bemoans" , "complaints" , "Sad songs" .)