The phrase "a sort of ball" is correct and usable in written English.
It can be used when describing something that resembles or has characteristics of a ball, but is not exactly a ball.
Example: "The object on the table was a sort of ball, made of colorful yarn and filled with soft stuffing."
Alternatives: "a kind of sphere" or "a type of orb".
"She stormed off and sort of collapsed into a sort of ball in the parking lot," Ms. Reynolds recalled.
Islam has "helped him to untangle a sort of ball of knots that he's dragged with him since his childhood," said his wife, the hip-hop singer Nawell Azzouz, known as Wallen.
Its train cars are too small for me to stand up straight, and I can't sit down, unless I curl up into a sort of ball and press my knees against my face.
And if the halfback can get any sort of ball on the hop, he can shred a D-line like the Ativa Professional Plus HDPro 2000, a noted shredder.
He had developed into a sort of wrecking ball of a centre as his career developed.
The site positioned itself as a sort of crystal ball for major world events, aggregating individual opinions and signaling the popular wisdom on, for instance, presidential elections.
"Inside her head is a sort of masked ball," Eva observes ruefully to Nick, speaking of her daughter's mercurial nature and tendency to fabricate.
Part protest and part projection, his characters' hectoring was a sort of wrecking ball that allowed Osborne to put outside himself the destruction that Nellie had put into him.
Not to be overlooked are leaf blowers as the instruments in a sort of beach-ball ballet and a comic musical sequence that brings onstage the Idiots and their band.
"The one thing that I think would be a mistake is to think of Lynton Crosby as a sort of crude, ball-busting Australian outsider.
It was a sort of alternative masked ball to fete an artist duo from Berlin who call themselves RothStauffenberg.
