The phrase "at his alert" is not correct and does not convey a clear meaning in written English.
It seems to be an attempt to express that someone is attentive or vigilant, but the phrasing is awkward and unclear.
Example: "He was always at his alert during the meeting, ready to respond to any questions."
Alternatives: "on high alert" or "at the ready".
At his alert best Cook would have ignored the delivery.
Forest's second-half pressure was relentless and De Vries needed to be at his alert best when substitute Nathan Tyson fired low moments after coming on.
Moreira, making his Swansea debut, had to be at his alert best as the Portuguese stopper made a super double save from Terry Gornell and then Morgan.
Lahr writes that Williams was at his "most alert, eloquent, humorous, vulnerable, and forthright when talking about the one pure thing in his life: his work".
And the Reds keeper had to be at his most alert when winger Walker thumped a shot at goal from 20 yards but, fortunately for the home side, it was aimed directly at their goalie.
"Suddenly, Senator Kennedy, seated directly across from me, looked at me with his alert, aristocratic eyes and asked me a most surprising question.
At his urging, they alert the shuttle to change its trajectory and they are able to land it successfully.
A blue jay, vivid in every feather, hung in the air motionless, like a hummingbird, but his wings stiffly at his sides, his eye alert like a bead of black glass.
On Tuesday, within 24 hours of John J. Gotti's death, Dennis Rigas put the staff on high alert at his flower shop in Richmond Hill, Queens.
Ton du Chatinier's side targeted Kelly's inexperience and occasionally prospered, with Reina alert at his near post to thwart Ricky van Wolfswinkel and Dries Mertens, but their wastefulness spared Liverpool throughout.
He described the bomb alert at his home as a "terrifying experience for my neighbours".
