The phrase "a rather formal" is correct and usable in written English.
It can be used to describe something that has a formal tone or style, often in contexts such as writing, speech, or attire.
Example: "The invitation was written in a rather formal manner, reflecting the significance of the event."
Alternatives: "somewhat formal" or "fairly formal".
He will then make a rather formal pronouncement.
Representational and abstract designs are usually combined in a rather formal, geometric manner.
A rather formal Englishman, a friend of ours who is giving some lectures at Harvard, took several of his shirts and stiff collars to a….
His best friend beamed, his aunt sang and wept and spat as a blessing, and his uncle gave him a rather formal pat on the head.
When asked a question, he will pause, apparently going into a dream state, muttering, "Yes… thinking". He will then make a rather formal pronouncement.
Note: the runway-way to carry these bags is at the side of your body in a rather formal fashion; a look that suits a sophisticated wool coat.
If that were the extent of the book, it would amount to an interesting, if rather formal, travelogue, another tale of a presumptuous Westerner finding enlightenment in the depths of primitive society.
It's a big painting, rather formal, about the materiality and physicality of close, but completely detached observation.
But the Factory Kitchen is a compelling new hybrid — an informal trattoria with rather formal northern Italian cooking, like those restaurants you sometimes find hidden in the warehouse districts of European cities that just happen to have a Michelin star.
Her social life suffered, and she acquired a reputation for being rather formal and distant.
Well into the first year of the recession, he marched forward as planned with a fairly expensive and rather formal restaurant in Chelsea.
