The most common and most likely answer to this crossword clue is the 7 letter word MOVABLE
I've seen this crossword clue in The Daily Telegraph
M
O
V
A
B
L
E
More clues leading to the result MOVABLE
Buddy explains!

The straight part
We know that "not being secure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not being secure = movable.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 MOVABLE mean?
MOVABLE noun- Something which is movable; an article of wares or goods; a commodity; a piece of property not fixed, or not a part of real estate; generally, in the plural, goods; wares; furniture.
- Capable of being moved, lifted, carried, drawn, turned, or conveyed, or in any way made to change place or posture; not fixed or stationary
- Changing from one time to another