Bell tower originally placed advantageously between two rivers (9)
I believe the answer is:
campanile
'bell tower' is the definition.
(campanile is a kind of bell tower)
'originally placed advantageously between two rivers' is the wordplay.
'two rivers' means two replacements for 'river'.
'originally' suggests taking the first letters.
'between' is an insertion indicator.
'river' becomes 'cam' (river in Cambridge, England).
'river' becomes 'nile' (Nile River is an example).
The first letters of 'placed advantageously' is 'pa'.
'cam'+'nile'='camnile'
'pa' put inside 'camnile' is 'CAMPANILE'.
(Other definitions for campanile that I've seen before include "Impale can on a bell-tower" , "In which bells are" , "Bell tower" .)