Final answer:
Hermione claims to be Penelope Clearwater when caught by Snatchers to avoid the persecution of Muggle-borns under Voldemort's regime in Harry Potter and the Deathly Hallows.
Step-by-step explanation:
When the trio, consisting of Harry, Hermione, and Ron, are caught by Snatchers in Harry Potter and the Deathly Hallows, Hermione uses a fake identity to protect herself and her friends. She claims to be Penelope Clearwater, who is supposed to be a half-blood rather than a Muggle-born. This is crucial because being a Muggle-born witch would have put her at immediate risk due to Lord Voldemort's regime which sought to persecute Muggle-borns.