The phrase "a certain shyness" is correct and usable in written English.
It can be used to describe a specific, but not fully defined, level of shyness in a person or situation.
Example: "Despite her outgoing nature, there was a certain shyness in her voice when she spoke about her artwork."
Alternatives: "a particular shyness" or "an undeniable shyness."
"There's a certain shyness that he has that draws him away from attention.
The Hare were noted for a certain shyness and reclusiveness from neighbouring Eskimo (Inuit) and other tribes.
Dr. Thompson also displayed modesty, patience and a certain shyness as he passed encouragement and knowledge to new generations of archaeologists, his colleagues and former students said.
But I could never, ever, in a million years, not feel tremendous irony, and a certain shyness, and a feeling of being abashed, if I continued in that way.
And yet, despite a certain shyness, Ayoade is quick-witted, erudite (he has a law degree from Cambridge) and far too fashionably attired ever to be confused with a genuine nerd.
Despite the growing vogue for 'kitchen sink dramas' at the time, he was still a working-class lad amid the middle-classes, held back by a certain shyness and those feelings of inferiority.
"There has been a certain cultural shyness about admitting it," said Frans de Waal, whose 1997 book, "Bonobo: The Forgotten Ape" (University of California Press), unleashed a torrent of discussion about animal sexuality.
HUBLEY: We were drawn to each other because we could recognize the same certain shyness in each other.
The idea might have reflected a certain gun-shyness by a justice not anxious to get back into the line of judicial fire.
Rabe grew up with a certain wariness, which passed as shyness.
"Those individuals, of which it will be certainly characterized by a common feature, namely a certain congenital or acquired working shyness and a resulting therefrom running tends to parasitize.
