Nervous reaction from heartless wife in chair (4,5)
I believe the answer is:
cold sweat
'nervous reaction' is the definition.
(I've seen this in another clue)
'heartless wife in chair' is the wordplay.
'heartless' becomes 'cold' (I've seen this in another clue).
'wife' becomes 'w' (abbreviation).
'in' indicates putting letters inside.
'chair' becomes 'seat' (something to sit on).
'w' put within 'seat' is 'sweat'.
'cold'+'sweat'='COLD SWEAT'
'from' is the link.
(Other definitions for cold sweat that I've seen before include "Symptom of fear" , "Chilly perspiration brought on by fear" , "Chilled perspiration" , "sign of fear" , "Symptom of nervousness or illness" .)