Either add a comma after 'colleague or, more informally, have no commas at all.

Student or Learner
I am wondering if my sentence is grammatically correct.
Phil's gut wrenched at the sight of his former colleague Ben, queuing at the food bank.
Either add a comma after 'colleague or, more informally, have no commas at all.
Interesting. Despite having used/heard/read "a gut-wrenching scream/shout" (other nouns are possible!) many times in my life, I don't think I've ever encountered "[name]'s gut wrenched".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
emsr2d2,
I am currently reading the novel "A Horse Walks into a Bar" by the Israeli writer David Grossman. It is translated from the Hebrew. After reading the following passage, I tried to write my own sentence. "Not far from me a woman slips her foot out of a narrow shoe and rubs it against the calf of her other leg, and my gut wrenches for the third or fourth time tonight – Tamara’s strong, solid legs – and I hear my own moan, the kind I’ve long ago forgotten."
I'm not disputing that it's usable. I was just commenting on the fact that I'd never seen it before.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.