Count up a large university club for one (7)
I believe the answer is:
dracula
'count' is the definition.
(Count Dracula)
'up a large university club for one' is the wordplay.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'large' becomes 'l'.
'university' becomes 'u' (abbreviation for university).
'club for one' becomes 'card' (clubs is a playing card suit).
'a'+'l'+'u'+'card'='alucard'
'alucard' backwards is 'DRACULA'.
(Other definitions for dracula that I've seen before include "Bram Stoker's batman" , "Famous vampire" , "Bram Stoker creation" , "Blood Count?" , "Fictional vampire" .)