The most common and most likely answer to this crossword clue is the 9 letter word RECURRENT
I've seen this crossword clue in The Guardian
R
E
C
U
R
R
E
N
T
Buddy explains!

The straight part
We know that "Habitual" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case habitual = recurrent.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 RECURRENT mean?
RECURRENT adjective- Recurring; happening time after time.
- (stochastic processes, of a state) Non-transient.
- Running back toward its origin.
- Turned back toward the base.