Possible Clues:

• Start of the holidays, a sea trip, goes awry
• Long holding up thank-you letter
• Hook starts the way he'd go on
• H like a peril of the sea
• Pronounce a leading H
• Begins hunting like a sea wolf
• In character of bad one at sea? Sound at start of horror
• Worrying at praise for such a letter
• 'ook doesn't have what it takes to succeed thus
• Breathe in