The phrase "most unclear" is grammatically correct and can be used in written English.
It is often used to emphasize the level of uncertainty or lack of clarity in a statement or situation. Example: "The instructions for assembling the furniture were most unclear, and I had to call customer service for clarification."
Most unclear of all was the expected result.
However, quite how the animal may have flown is most unclear.
The issue that remains most unclear is whether the team will add a secondary fence in left field in front of the original one.
What's most unclear on American campuses today is whether students will deign to veer their attention from the accents of foreign teachers long enough to realize all they have to offer beyond it.
And – both most importantly and most unclear – they could not bring Paragraph IV invalidity counterclaims under Hatch-Waxman, preventing generic companies from independently challenging patents' invalidity and potentially requiring us all to wait until the very end of patent expiration to experience generic competition.
This latter result indicates that it is relationships between the northern European and South Asian assemblages that are most unclear, while the major pattern of branching between African versus non-African assemblages is robustly supported.
The position and rights of Scottish peers in relation to the House of Lords remained unclear during most of the eighteenth century.
The details of how many injuries over what period of time and at what ages lead to what health consequences acutely or in the long-term is, for the most part, unclear.
What those might have been is, for the most part, unclear.
However, the origin of circulating miRNAs is in most instances unclear.
The biological effects of these particles and their corrosion products in the human body are for the most part unclear.
