A tad wet swimming round river... um - just stay afloat (5,5)
I believe the answer is:
tread water
'stay afloat' is the definition.
(I've seen this before)
'a tad wet swimming round river um' is the wordplay.
I cannot quite see how this works, but
'a' is present in the answer.
'wet' could be 'water' (watering is a kind of wetting) and 'water' is present in the answer.
'river' could be 'red' (Red is an example) and 'red' is found within the remaining letters.
A single letter 't' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'just' acts as a link.
Can you help me to learn more?
(Other definitions for tread water that I've seen before include "Make little or no progress" , "having no solid base" , "Stay afloat" , "fail to make progress!" , "unwilling to go with the flow?" .)