The most common and most likely answer to this crossword clue is the 10 letter word ATTAINMENT
I've seen this crossword clue in The Times
A
T
T
A
I
N
M
E
N
T
More clues leading to the result ATTAINMENT
- Feat involving Tim and Netta, not daughter
- Participating in the regatta in Menton is a feat
- Soldiers in disgrace or laudable exploit
- At Territorial Army in time to capture soldiers, showing talent
- Acquisition of rough mat in a tent
- The achievement of a teetotaller isn’t commonly welcoming people
- A mint spent in a covered place for acquisition
- People in a series of races have not commonly achieved goal
- Busy with getting rid of record of fun feat
- Ann and I met two times, a remarkable accomplishment
Buddy explains!

The straight part
We know that "Feat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case feat = attainment.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 ATTAINMENT mean?
ATTAINMENT noun- The act of attaining; the act of arriving at or reaching; the act of obtaining by exertion or effort.
- That which is attained, or obtained by exertion; acquisition; acquirement.