The most common and most likely answer to this crossword clue is the 10 letter word TANTAMOUNT
I've seen this crossword clue in The Times
T
A
N
T
A
M
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U
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T
More clues leading to the result TANTAMOUNT
- Brown horse fed regular helpings of straw or equivalent
- Equivalent to whip that’s regularly used on horse
- Silly man, to get taken in by tease or equivalent
- It’s more or less important a mountaineer carries it
- The same as having to flog endless rubbish to get on
- The same as blood group found in mutant ant? Not exactly
- Equivalent shift’s ultimate worker gets a rise
- Equal number beat time beforehand
- Equal beat at climbing tor
- Not a mutant alien, or equivalent
Buddy explains!

The straight part
We know that "equivalent" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case equivalent = tantamount.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 TANTAMOUNT mean?
TANTAMOUNT noun- Something which has the same value or amount (as something else). (attributive use passing into adjective, below)
- To amount to as much; to be equivalent.
- Equivalent in meaning or effect; amounting to the same thing in practical terms, even if being technically distinct.