Son gets off craft (5)
I believe the answer is:
skill
'craft' is the definition.
(thesaurus)
'son gets off' is the wordplay.
'son' becomes 's'.
'gets' says to put letters next to each other.
'off' becomes 'kill' ('off' can informally mean 'murder').
's'+'kill'='SKILL'
(Other definitions for skill that I've seen before include "Special ability" , "Ability - dexterity" , "Prowess" , "Craft; dexterity" , "Aptitude" .)