River keeping cool for convenience (6)
I believe the answer is:
urinal
'convenience' is the definition.
(I've seen this before)
'river keeping cool' is the wordplay.
'river' becomes 'ural' (I've seen this before).
'keeping' means one lot of letters goes inside another.
'cool' becomes 'in' ('in' can mean fashionable or cool).
'ural' going around 'in' is 'URINAL'.
'for' is the link.
(Other definitions for urinal that I've seen before include "public convenience" , "Sanitary fitting" , "waste disposal unit" .)