Financial interest in the post? (5)
I believe the answer is:
stake
I believe this clue is a double definition.
'financial interest' is the first definition.
(I've seen this in another clue)
'the post?' is the second definition.
('stake' can be a synonym of 'post')
'in' acts as a link.
(Other definitions for stake that I've seen before include "Money placed as bet" , "Sum gambled" , "Amount wagered" , "Prize" , "Financial interest" .)