Persuaded to include loud supporting character from Dickens's pen (9)
I believe the answer is:
sheepfold
'pen' is the definition.
(sheepfold is a kind of pen)
'persuaded to include loud supporting character from dickens's' is the wordplay.
'persuaded' becomes 'sold' (to sell someone an idea is to persuade them of it).
'to include' is an insertion indicator.
'loud' becomes 'f' (A musical term).
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'character from dickens' becomes 'heep' (Uriah Heep, David Copperfield character).
'f' put after 'heep' is 'heepf'.
'sold' enclosing 'heepf' is 'SHEEPFOLD'.
(Other definitions for sheepfold that I've seen before include "Farm pen" , "Pen for lambs, ewes, etc" .)