The most common and most likely answer to this crossword clue is the 10 letter word STIR-CRAZY
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More clues leading to the result STIR-CRAZY
Buddy explains!

The straight part
We know that "like a lock-down sufferer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case like a lock-down sufferer = stir-crazy.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 STIR-CRAZY mean?
STIR-CRAZY adjective- Of a prisoner, mentally unbalanced due to prolonged incarceration.
- (by extension) Restless, uncomfortable, or impatient due to inactivity or confinement.