Some ground grass spread around lake (4)
I believe the answer is:
plot
'some ground' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'grass spread around lake' is the wordplay.
'grass' becomes 'pot' (cannabis).
'spread around' is an insertion indicator.
'lake' becomes 'l' (geographical abbreviation).
'pot' going around 'l' is 'PLOT'.
Can you help me to learn more?
(Other definitions for plot that I've seen before include "Ground - plan" , "part of garden" , "Draw (graph)" , "Mark position" , "Scheme, story and piece of ground" .)