The most common and most likely answer to this crossword clue is the 10 letter word PRETENDING
I've seen this crossword clue in The Daily Telegraph
P
R
E
T
E
N
D
I
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G
More clues leading to the result PRETENDING
- Daughter’s into grooming over time, keeping up appearances
- Acting priest is missing from the finale
- Priest getting top from emporium, leaning and putting it on
- Putting on an act before start of theatrical finale
- Acting quietly, get dinner served
- Going through the motions before moving
- Falsely claiming Macron’s ready with resolution
Buddy explains!

The straight part
We know that "Falsely claiming" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case falsely claiming = pretending.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 PRETENDING mean?
PRETENDING verb- To claim, to allege, especially when falsely or as a form of deliberate deception.
- To feign, affect (a state, quality, etc.).
- To lay claim to (an ability, status, advantage, etc.). (originally used without to)
- To make oneself appear to do or be doing something; to engage in make-believe.
- To hold before, or put forward, as a cloak or disguise for something else; to exhibit as a veil for something hidden.
- To intend; to design, to plot; to attempt.
- To hold before one; to extend.
- The act of imagining; make-believe