O'Connor perhaps is unable to provide accompaniment (7)
I believe the answer is:
descant
'accompaniment' is the definition.
(I know that descant is a type of accompaniment)
'o'connor perhaps is unable' is the wordplay.
I cannot really see how this works, but
'o'connor' could be 'des' (entertainer Des O'Connor) and 'des' is present in the answer.
'is unable' could be 'cant' (I've seen this in another clue) and 'cant' is present in the answer.
No letters remain.
This may be the basis of clue (or it may be nonsense).
'to provide' acts as a link.
Can you help me to learn more?
(Other definitions for descant that I've seen before include "Independent melody sung above a basic melody" , "Ornamental melody added above a theme" , "Independent treble line" , "Accompaniment added above a basic melody" , "Highest range (eg of a 10)" .)