Pull everyone on river (6)
I believe the answer is:
allure
'pull' is the definition.
(I've seen this in another clue)
'everyone on river' is the wordplay.
'everyone' becomes 'all' (all people).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'river' becomes 'ure' (River Ure).
'all'+'ure'='ALLURE'
(Other definitions for allure that I've seen before include "Charm, magnetism" , "What siren may do" , "Glamorous appeal" , "Attraction, appeal" , "Tempt" .)