Decline to accept one shilling for fund (9)
I believe the answer is:
subsidise
'fund' is the definition.
('fund'->'subsidize' is in my internal thesaurus and 'ize'->'ise')
'decline to accept one shilling' is the wordplay.
'decline' becomes 'subside' (I've seen this before**).
'to accept' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'shilling' becomes 's'.
'i'+'s'='is'
'subside' enclosing 'is' is 'SUBSIDISE'.
'for' is the link.
(Other definitions for subsidise that I've seen before include "Pay part of the cost of producing something" , "Pay a grant towards" , "Support financially" , "Support through grants" , "Give a grant towards" .)