Cryptic crossword clue
One obsessively follows speech in sermon, half cut 7

The most common and most likely answer to this crossword clue is the 7 letter word STALKER

I've seen this crossword clue in The Daily Telegraph
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Buddy explains!

The straight part
We know that "One obsessively follows" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one obsessively follows = stalker.
The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.
This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.

What does STALKER mean?

STALKER noun
  1. A person who engages in stalking, i.e. quietly approaching animals to be hunted; a tracker or guide in hunting game.
  2. A person who secretly follows someone, sometimes with unlawful intentions.
  3. Any of various devices for removing the stalk from plants during harvesting.
  4. Any bird that walks with a stalking motion.
  5. A kind of fishing net.

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