Perform in river? Lovely (7)
I believe the answer is:
execute
'perform' is the definition.
(I know that perform can be written as execute)
'river? lovely' is the wordplay.
'river?' becomes 'exe' (River Exe).
'lovely' becomes 'cute' (I can't justify this - if you can you should believe this answer much more).
'exe'+'cute'='EXECUTE'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for execute that I've seen before include "Carry out; behead" , "Put (plan) into effect; kill (a condemned person)" , "Inflict capital punishment upon" , "ice" , "Put to death - put into effect" .)