The most common and most likely answer to this crossword clue is the 7 letter word TREFOIL
I've seen this crossword clue in The Times
T
R
E
F
O
I
L
More clues leading to the result TREFOIL
- Whistler painting attributed to Turner at first — that's a bloomer
- Official work clothes for plant
- Plant finally sent soldiers sword
- Official stops work in plant
- Sort of knot judge has to work round
- Sweat-covered man in middle of field finding shamrock?
- Arbiter consumed by work in plant-BEAR
- Whistle-blower stops hard labour in plant
- Loftier spreading plant
- Plant person on field to get stuck into work
Buddy explains!

The straight part
We know that "bloomer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bloomer = trefoil.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 TREFOIL mean?
TREFOIL noun- Any of several plants of the pea family, having compound, trifoliate leaves; especially one of the genus Trifolium.
- A symbol having the shape of such leaves, especially when used as an architectural ornament.
- A knot formed by joining the two loose ends of a overhand knot to form a knotted loop; the simplest non-trivial knot.