The phrase "a shaky grasp" is correct and usable in written English.
It can be used to describe someone’s uncertain or weak understanding of a subject or concept.
Example: "Despite studying for weeks, she still had a shaky grasp of the material during the exam."
Alternatives: "a tenuous understanding" or "a weak hold".
She also showed a shaky grasp of her portfolio, humanitarian aid.
Even with a shaky grasp of our parts, we're whipping up a massive, stinging cloud of noise.
Jack has a shaky grasp on time and language — events could have happened days ago, or years, or a word can easily slip free of its meaning.
It's pretty clear that even the cast have a shaky grasp of the offside rule, and the goals are mostly scored with a ball on a stick.
Chief Justice John Roberts, who wrote Wednesday's opinion, showed what could politely be described as a shaky grasp of technology during oral arguments in multiple cases this term.
It got its wish: the government — if it holds together — will be fractured and unwieldy, rife with suspicion, hobbled by a shaky grasp of the rule of law and prone to collapse, or at least chaos.
"Extensive research, however, has convinced me that the beast in question was a Common Welsh Green whose legs were counted by a Muggle with a very shaky grasp of numeracy … It is always a blow to have a cherished part of one's life dismissed as a figment of the imagination … but we wizards have to deal with that every day".
And another: "If you share your whole life on social media who cares if the government takes a peek?!?" These citizens have a somewhat shaky grasp of how civil liberties are supposed to work.
On 19 July 2011, as the committee of MPs questioned Keith Rupert Murdoch, known to most simply as Rupert, about the hard facts of the News of the World phone hacking scandal, viewers around the world saw a father with an apparently shaky grasp defer to his son, James.
McDonnell, like Allen, seems to have a rather shaky grasp of the principles of intellectual inquiry.
In English, many showed a similarly shaky grasp of punctuation with almost one in four admitting to not knowing when to use a semi-colon (23%); 18% the rules governing the use of an apostrophe; and 17% when to use a comma.
