Leave floating on the river for show (6)
I believe the answer is:
reveal
'show' is the definition.
(revealing is a kind of showing)
'leave floating on the river' is the wordplay.
'floating' is an anagram indicator (float can mean fluctuate or oscillate).
'on' means one lot of letters goes inside another (as in clothing 'on' a person).
'the river' becomes 'r' (abbreviation).
'leave' with letters rearranged gives 'eveal'.
'eveal' placed around 'r' is 'REVEAL'.
'for' is the link.
(Other definitions for reveal that I've seen before include "Divulge; make visible" , "Make known to others" , "Make known, expose" , "Disclose or uncover" , "Make known or visible" .)