The most common and most likely answer to this crossword clue is the 6 letter word CATKIN
I've seen this crossword clue in The Daily Telegraph
C
A
T
K
I
N
More clues leading to the result CATKIN
Buddy explains!

The straight part
We know that "flower" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case flower = catkin.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 CATKIN mean?
CATKIN noun- A type of inflorescence, consisting of an axis with many unisexual apetalous flowers along its sides, as in the willow and poplar.