The most common and most likely answer to this crossword clue is the 10 letter word PRETENSION
I've seen this crossword clue in The Daily Telegraph
P
R
E
T
E
N
S
I
O
N
More clues leading to the result PRETENSION
- Unjustifiable claim before leading to strain
- Pomposity of pensioner worked up about the ending of Brexit
- Stretch before casting for show
- … before strained situation leads to unjustified claim
- In advance, give a sort of force to claim
- Claim source of emotional stress is supporting Spurs regularly
- Claim to be retired, existing within post-work allowance?
- Stress follows before making claim
Buddy explains!

The straight part
We know that "Claim" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case claim = pretension.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 PRETENSION mean?
PRETENSION noun- A claim or aspiration to a particular status or quality.
- Pretentiousness.
- To apply tension to an object before some other event or process.
- To apply tension to reinforcing strands before concrete is poured in.