The most common and most likely answer to this crossword clue is the 11 letter word DETRIMENTAL
I've seen this crossword clue in The Times
D
E
T
R
I
M
E
N
T
A
L
More clues leading to the result DETRIMENTAL
- Harmful crackers placed on lectern regularly seized by cop
- Recklessly altered, mint can become harmful
- Causing harm for the teeth eating alien marge
- In time, right filling of teeth can be damaging
- Damaging tooth, base of blade cut into it
- Recklessly altered mint causing harm
- Tired out, unstable and causing harm
- Tired out chaps returning belatedly, mostly – it’s bad
- Awfully tired intellectual becomes harmful
- Tired out in the mind, which is bad for one
Buddy explains!

The straight part
We know that "Damaging" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case damaging = detrimental.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 DETRIMENTAL mean?
DETRIMENTAL adjective- Causing damage or harm.