Place where men go when river floods home (6)
I believe the answer is:
urinal
'place where men go' is the definition.
(as in 'going' to the toilet)
'river floods home' is the wordplay.
I cannot quite see how this works, but
'river' could be 'r' (abbreviation for river) and 'r' is found in the answer.
'home' could be 'in' ('he's home' can mean 'he's in') and 'in' is present in the answer.
This explanation may well be incorrect...
'when' acts as a link.
Can you help me to learn more?
(Other definitions for urinal that I've seen before include "waste disposal unit" , "Sanitary fitting" , "public convenience" .)