The phrase "a substantial enough" is correct and usable in written English.
It can be used when discussing the adequacy or sufficiency of something, often in terms of quantity or quality.
Example: "We need to ensure that we have a substantial enough budget to cover all project expenses."
Alternatives: "sufficiently substantial" or "adequately substantial".
"It is a substantial enough niche market for Sears," Mr. Bagla said.
Maybe Apple's plastic iPhone stand doesn't seem a substantial enough vessel for your beloved 4S.
If that doesn't count as a substantial enough change to warrant re-review then what possibly could?
The city, Mr. Patterson said, "wanted a substantial enough project to make a positive impact downtown and attract buyers".
As Alan Dranow explained to me, "It's an expensive proposition that would not likely show a substantial enough return on the investment in a tangible way".
The opinion concluded that the need to bar even threats of violence against the country was "a substantial enough interest" to limit First Amendment freedoms.
Military leaders and President Obama's civilian advisers are girding for battle over the size and pace of the planned pullout of U.S. troops from Afghanistan this summer, with the military seeking to limit a reduction in combat forces and the White House pressing for a withdrawal substantial enough to placate a war-weary electorate.
Until he was over thirty he lived at Earlsfield, a mansion substantial enough to house a British embassy in later years, an active young man already inclining to stoutness.
But with the Internet eating into Condé Nast's profits, McKinsey & Company came in to help reduce overhead, and there was concern about whether an art magazine could actually amass a circulation substantial enough to make it a viable business for the Newhouses.
Others never reach the top 20 but amass a following substantial enough to sustain a decades-long career.
After the release of Microsoft's Xbox One S earlier this month – a smaller, totally whiter version of the original Xbox One, a console substantial enough to puncture the hull of a small yacht if dropped from waist height – comes Sony's own shrinking of its current-gen hardware.
