The most common and most likely answer to this crossword clue is the 6 letter word CHOLLA
C
H
O
L
L
A
Buddy explains!
The straight part
We know that "cactus" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cactus = cholla.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 CHOLLA mean?
CHOLLA noun- Any of several species of cactus in the genus Cylindropuntia, having very spiny, cylindrical stem segments.