The most common and most likely answer to this crossword clue is the 6 letter word SEQUEL
I've seen this crossword clue in The Daily Telegraph
S
E
Q
U
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L
More clues leading to the result SEQUEL
- Follower in Paris that stops overthrow of the French
- Suite surrounding queen with happiness
- Endlessly understand and subdue Part 2?
- What follows search for fleece, according to storyteller?
- Follow line purchasing Queen follow-up
- Heads of space exploration largely put down a film like Aliens
- London area curtailed crush — film later showing?
- Ongoing saga of refit for useless ship set aside to accommodate queen
- Succeeded with identical-sounding follow-up
- Part 2: Paraphrase ‘quelque part’
Buddy explains!

The straight part
We know that "follow-up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case follow-up = sequel.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 SEQUEL mean?
SEQUEL noun- The events, collectively, which follow a previously mentioned event; the aftermath.
- A narrative that is written after another narrative set in the same universe, especially a narrative that is chronologically set after its predecessors, or (perhaps improper usage) any narrative that has a preceding narrative of its own.
- Thirlage.
- A person's descendants.