The most common and most likely answer to this crossword clue is the 7 letter word OPACITY
I've seen this crossword clue in The Times
O
P
A
C
I
T
Y
More clues leading to the result OPACITY
- Lack of transparency — and compassion — when handling bill
- Old father’s place shows a lack of clearness
- Dullness in the work cited one’s opened
- Work associated with a financial centre lacks transparency
- Lack of clarity in account swathed in love and compassion
- Lack of transparency in a business community undermining work
- Cloudiness over outskirts of Palma town
- Obstruction of light work by a financial district
- Cover rolled up and put inside the oddity with the missing cleric showed cloudiness
- Cloudiness is beginning to overwhelm the outskirts of Patiala town
Buddy explains!

The straight part
We know that "Lack of transparency" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lack of transparency = opacity.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 OPACITY mean?
OPACITY noun- The state or quality of being opaque, not allowing light to pass through
- The state or quality of being inaccessible to understanding.
- A measure of relative impenetrability to electromagnetic radiation such as light.