Finished plan creating bank facility for customers (9)
I believe the answer is:
overdraft
'bank facility for customers' is the definition.
(as in an overdraft on a bank account)
'finished plan' is the wordplay.
'finished' becomes 'over' (similar in meaning).
'plan' becomes 'draft' (drafting is a kind of planning).
'over'+'draft'='OVERDRAFT'
'creating' acts as a link.
(Other definitions for overdraft that I've seen before include "Debit balance in bank account" , "money that must be repaid" , "figure in red?" , "Red balance" , "shows lack of balance" .)