Scrooge in almost complete despair (5)
I believe the answer is:
miser
'scrooge' is the definition.
(Dickens' Ebenezer Scrooge is a miser)
'almost complete despair' is the wordplay.
'almost complete' means to remove the last letter (most but not all of the word).
'despair' becomes 'misery' (I've seen this before).
'misery' with its final letter taken away is 'MISER'.
'in' acts as a link.
(Other definitions for miser that I've seen before include "One sparing with money" , "Someone close" , "One such as Scrooge" , "auger" , "Hoarder of money and possessions" .)