The most common and most likely answer to this crossword clue is the 9 letter word CORROSIVE
I've seen this crossword clue in The Times
C
O
R
R
O
S
I
V
E
More clues leading to the result CORROSIVE
- Acid destroying visor core
- Vitriolic old bishop beset by turbulent voices
- Lifting mask, in essence, is damaging
- Hurtful, shade reflective having broken heart
- Blimey! Got up around four and eating away
- Caustic substance coating backward cap’s brim
- I say wine brought about the onset of indigestion — very acidic
Buddy explains!

The straight part
We know that "acidic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case acidic = corrosive.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 CORROSIVE mean?
CORROSIVE noun- That which has the quality of eating or wearing away gradually.
- Any solid, liquid or gas capable of irreparably harming living tissues or damaging material on contact.
- Eating away; having the power of gradually wearing, hanging, or destroying the texture or substance of a body; as the corrosive action of an acid.
- Having the quality of fretting or vexing.
- Destroying or undermining something gradually.