Dickensian character goes mad about return of monster (7)
I believe the answer is:
scrooge
'dickensian character' is the definition.
(I've seen this before)
'goes mad about return of monster' is the wordplay.
'mad' indicates an anagram.
'about' is an insertion indicator.
'return of' shows that the letters should be reversed in order.
'monster' becomes 'orc' (fantasy creature).
'orc' back-to-front is 'cro'.
'goes' anagrammed gives 'soge'.
'soge' placed around 'cro' is 'SCROOGE'.
(Other definitions for scrooge that I've seen before include "Ebenezer ......., miser created by Dickens" , "'A Christmas Carol' character" , "One mean with money" , "Mean person" , "Dickens' skinflint (7)" .)