Stroke of genius ultimately after worries (6)
I believe the answer is:
caress
'stroke' is the definition.
(I know that caress is a type of stroke)
'genius ultimately after worries' is the wordplay.
'ultimately' says to take the final letters.
'after' means one lot of letters go next to another.
'worries' becomes 'cares' (I've seen this in another clue).
The final letter of 'genius' is 's'.
's' after 'cares' is 'CARESS'.
'of' is the link.
(Other definitions for caress that I've seen before include "Tenderly stroke" , "Stroke affectionately" , "Gentle stroke" , "Stoke affectionately" , "Gentle affectionate stroking" .)