Forking out to cover outrageous bill is charming (12)
I believe the answer is:
spellbinding
'charming' is the definition.
(spellbinding is a kind of charming)
'forking out to cover outrageous bill' is the wordplay.
'forking out' becomes 'spending' (to fork out is to spend a lot of money).
'to cover' means one lot of letters goes inside another.
'outrageous' indicates anagramming the letters (I've seen this in other clues).
'bill' anagrammed gives 'llbi'.
'spending' placed around 'llbi' is 'SPELLBINDING'.
'is' acts as a link.
(Other definitions for spellbinding that I've seen before include "Fascinating" , "Engrossing" , "Enthralling" .)