A blow to the heart would nauseate (3,3)
I believe the answer is:
put off
'nauseate' is the definition.
(thesaurus)
'a blow to the heart would' is the wordplay.
I cannot quite see how this works, but
'to' is found in the answer.
'blow' could be 'puff' (puffing is a kind of blowing) and 'puff' is located in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for put off that I've seen before include "Don't encourage - delay" , "Defer to a later time, or alienate" , "confuse" , "Deter; deterred" , "Deter; delayed" .)