The most common and most likely answer to this crossword clue is the 6 letter word BALDIE
I've seen this crossword clue in Independent
B
A
L
D
I
E
More clues leading to the result BALDIE
Buddy explains!

The straight part
We know that "one without locks" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one without locks = baldie.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 BALDIE mean?
BALDIE noun- Somebody who is bald.
- The bald eagle (Haliaeetus leucocephalus).
- A fish, the baldchin groper.