The most common and most likely answer to this crossword clue is the 7 letter word RUINOUS
I've seen this crossword clue in Independent
R
U
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N
O
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S
More clues leading to the result RUINOUS
- Ball game, I sense, doing massive harm
- Catastrophic game in old America
- Crippling game in old America
- Peeled fruit almost useless, decayed
- Our US, it seems, is catastrophic
- Contact sport is about number united falling down
- Dire game across Atlantic, involving ball
- What suggests our US is causing destruction?
- It’s catastrophic, when promissory notes run out
- Very expensive seat of learning located in what’s left of medieval castle?
Buddy explains!

The straight part
We know that "catastrophic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case catastrophic = ruinous.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 RUINOUS mean?
RUINOUS adjective- Causing ruin; destructive, calamitous
- Extremely costly; so expensive as to cause financial ruin.
- Characterized by ruin; ruined; dilapidated; as, an edifice, bridge, or wall in a ruinous state.