Close tight fist around a plotter's heart (4,2,4)
I believe the answer is:
near at hand
'close' is the definition.
(I've seen this in another clue)
'tight fist around a plotter's heart' is the wordplay.
'tight' becomes 'near' (I've seen this in other clues).
'fist' becomes 'hand' (I have seen 'Unclenched fist' mean 'hand' so perhaps 'fist' could also mean 'hand').
'around' indicates putting letters inside.
'a plotter's heart' becomes 'at' (I can't explain this - if you can you should believe this answer much more).
'near'+'hand'='nearhand'
'nearhand' enclosing 'at' is 'NEAR AT HAND'.
Can you help me to learn more?
(Other definitions for near at hand that I've seen before include "Native of NE England area" , "Close by" .)