It’s a malediction: you can swear it! (4)
I believe the answer is:
oath
This could be a double definition.
'it's a malediction' is the first definition.
(I've seen this in another clue)
'can swear it' is the second definition.
I know that 'swear' relates to this answer.
'you' is the link.
Can you help me to learn more?
(Other definitions for oath that I've seen before include "Solemn pledge" , "Vow; profanity" , "Tedious task" , "A curse or a vow" , "in court, we take it" .)