Own up is an idiom that means to take responsibility for one's actions, usually by admitting to a mistake or wrongdoing. The crossword solutions for this term are GRANT (5 letters), AVOW (4 letters), ADMIT (5 letters), CONFESS (7 letters), fess (4 letters), and TELL (4 letters). All of these words can be used to describe the act of owning up, as they all involve taking responsibility for something and being honest about it.