The most common and most likely answer to this crossword clue is the 6 letter word TEASEL
I've seen this crossword clue in The Daily Telegraph
T
E
A
S
E
L
More clues leading to the result TEASEL
- Something prickly left under rag
- Quite a selection including prickly plant
- Tickle large prickly head
- Oddly, they answer to Liberal leader
- Pull gently on large plant
- Plant stand supporting head of tulip
- Plant left behind rag
- Poke fun at suspicion of lady’s bristly growth
- Plant stand put on front of terrace
- Grant requires particular envelope to return prickly plant
Buddy explains!

The straight part
We know that "Plant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case plant = teasel.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 TEASEL mean?
TEASEL noun- Any of several plants of the genus Dipsacus.
- The dried flower head of the fuller's teasel, Dipsacus fullonum, used for teasing or carding cloth.
- Any contrivance intended as a substitute for teasels in dressing cloth.
- To raise the nap on cloth; to tease; to card.