The phrase "a commentator on a" is correct and usable in written English.
It can be used when referring to someone who provides commentary or analysis on a specific topic or subject.
Example: "As a commentator on a variety of political issues, she offers unique insights during debates."
Alternatives: "an analyst of a" or "a critic of a".
A breathless biography on Avenatti's website says he "routinely appears on television and in the print media as a commentator on a range of issues and is widely considered one of the foremost trial lawyers in the nation".
He has also been a commentator on a variety of television and radio programs.
A commentator on a motorbike dropped back to ask the Texan's team manager Johan Bruyneel what was going on.
Krishna Chaitanya, a commentator on a recent HBR post, wrote that the the best words are spoken with the most honest, curious (not challenging), and genuine voice.
As a commentator on a CBS radio show and a columnist for The San Jose Mercury News, Magid sometimes criticizes the company but has defended it at key moments.
In response to Mr. Rubin, a commentator on a Wikipedia discussion page, Tom Harrison, wrote: "Like most fringe subjects it has been unduly (and unintentionally, in most cases) promoted, giving readers and maybe search engines an impression of cultural significance that isn't supported to that extent in reliable sources.
A commentator on an article in the New Yorker filled in many of the gaps.
On one side are those bemused by the network's apparent need to draw further attention to an seemingly harmless heat of the moment observation by a commentator on an incident in a football match.
Wilson was a commentator on an EPRI-sponsored roundtable last year on an earlier round of quarreling climate cost models put forward by CRA International, U.S. EPA, the Energy Information Administration, the Clean Air Task Force and the American Council on Capital Formation.
He also worked frequently as an commentator on NFL telecasts and as a spokesperson for a vast number of products.
They also check in with the public: Dugard wrote a bestselling memoir, "A Stolen Life," and Elizabeth Smart, a commentator on ABC about issues of domestic violence, will be publishing one of her own in October.
