Bad language from son? Exhausting (8)
I believe the answer is:
swearing
'bad language' is the definition.
(thesaurus)
'son? exhausting' is the wordplay.
'son?' becomes 's'.
'exhausting' becomes 'wearing' ('wearing' can be a synonym of 'exhausting').
's'+'wearing'='SWEARING'
'from' is the link.
(Other definitions for swearing that I've seen before include "Using bad language" , "blue emissions?" , "Vowing" , "Expressing annoyance" , "Affirming or cursing" .)