The most common and most likely answer to this crossword clue is the 7 letter word MISTIER
I've seen this crossword clue in The Daily Telegraph
M
I
S
T
I
E
R
Buddy explains!

The straight part
We know that "more obscure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case more obscure = mistier.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 MISTIER mean?
MISTIER adjective- Covered in mist; foggy.
- Dim; vague; obscure.
- With tears in the eyes; dewy-eyed.