Charm everyone by river (6)
I believe the answer is:
allure
'charm' is the definition.
(I've seen this before)
'everyone by river' is the wordplay.
'everyone' becomes 'all' (all people).
'by' says to put letters next to each other.
'river' becomes 'ure' (River Ure).
'all'+'ure'='ALLURE'
(Other definitions for allure that I've seen before include "Entice or attract - sounds like a decoy" , "The power to entice or attract" , "Enticement, attraction" , "Tempt" , "Powerful fascination" .)