Serious error having son home (3)
I believe the answer is:
sin
'serious error' is the definition.
(I've seen this before)
'son home' is the wordplay.
'son' becomes 's'.
'home' becomes 'in' ('he's home' can mean 'he's in'**).
's'+'in'='SIN'
'having' acts as a link.
(Other definitions for sin that I've seen before include "Wicked deed" , "Wickedness" , "Depravity" , "'Transgression, mortal or venial (3)'" , "Serious transgression" .)