Waste material found at the bottom of 2 down on a lake (5)
I believe the answer is:
offal
'waste material' is the definition.
(I've seen this before)
'at the bottom of 2 down on a lake' is the wordplay.
'at the bottom of' is a charade indicator (letters next to each other).
'f down' becomes 'off' (I can't justify this - if you can you should give a lot more credence to this answer).
'on' is a charade indicator (letters next to each other).
'lake' becomes 'l'.
'off'+'a'='offa'
'offa' put next to 'l' is 'OFFAL'.
'found' is the link.
Can you help me to learn more?
(Other definitions for offal that I've seen before include "Butcher's leftovers" , "Animal entrails and internal organs - worthless" , "cheap meat" , "Edible insides" , "Entrails/organs as food" .)