Irritant gas about Mars causing stroke (6)
I believe the answer is:
caress
'stroke' is the definition.
(I know that caress is a type of stroke)
'irritant gas about mars' is the wordplay.
'irritant gas' becomes 'cs' (short for 2-chlorobenzalmalononitrile. I am not sure about the 'irritant' bit.).
'about' indicates putting letters inside.
'mars' becomes 'ares' (I've seen this in another clue).
'cs' going around 'ares' is 'CARESS'.
'causing' is the link.
Can you help me to learn more?
(Other definitions for caress that I've seen before include "Expression of affection" , "Scares into handle lovingly" , "Gentle loving touch" , "Scares with loving stroke" , "Stroke lightly in a loving manner" .)