Now there's a piece of wood in the river (5)
I believe the answer is:
today
'now' is the definition.
(I know that now can be written as today)
'a piece of wood in the river' is the wordplay.
'a piece of wood' becomes 'od' (I can't explain this - if you can you should give a lot more credence to this answer).
'in the' means one lot of letters goes inside another.
'river' becomes 'tay' (Scottish river).
'od' placed within 'tay' is 'TODAY'.
'there's' is the link.
Can you help me to learn more?
(Other definitions for today that I've seen before include "12, 12" , "Nowadays" , "Current period of 24 hours" , "Presently" , "The present time or age" .)