Clear Devon waters hosting unique rodent (9)
I believe the answer is:
exonerate
'clear' is the definition.
(to clear of criminal charges)
'devon waters hosting unique rodent' is the wordplay.
'devon waters' becomes 'Exe' (the River Exe).
'hosting' indicates putting letters inside (inserted letters are welcomed in or hosted).
'unique' becomes 'one' (synonyms).
'rodent' becomes 'rat' (rat is a kind of rodent).
'one'+'rat'='onerat'
'exe' going around 'onerat' is 'EXONERATE'.
(Other definitions for exonerate that I've seen before include "let off the hook" , "Pronounce not guilty of a crime" , "Excuse" , "Clear of blame" , "Free from obligation, blame" .)