In essence, a strong point (4)
I believe the answer is:
east
'point' is the definition.
(I know that east is a type of cardinal compass point)
'in essence a strong' is the wordplay.
'in' says the answer is hidden in the clue.
'EAST' is hidden in the letters of 'essence a strong'.
(Other definitions for east that I've seen before include "the way the Wise Men came from" , "Compass direction" , "Where the sun rises" , "Upset seat in one direction" , "Player in deal" .)