Have something to confess (3)
I believe the answer is:
own
'confess' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for own that I've seen before include "Possess or confess" , "Allow" , "Keep" , "Be in legal possession of (3)" , "Posses" .)