The most common and most likely answer to this crossword clue is the 6 letter word LICHEN
I've seen this crossword clue in Independent
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More clues leading to the result LICHEN
- Right about child’s skin eruption
- Vegetation right outside church
- Eruption, hot, in Iceland and going of explosively – little new
- Plant put right outside the church
- Loudly compare fungus and alga
- In speech, compare fungus and alga
- Anthropomorphic lichen has wearied expression
- . Using chlorine, men come up with skin disease
- Large niche designed for thing growing among stones, say
- Verbally compare fungus with algae
Buddy explains!

The straight part
We know that "Vegetation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vegetation = lichen.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 LICHEN mean?
LICHEN noun- Any of many symbiotic organisms, being associations of algae and fungi, often found as white or yellow patches on old walls, etc.
- Something which gradually spreads across something else, causing damage.