The phrase "a former collaborator" is correct and usable in written English.
It can be used to refer to someone who previously worked together with another person or group on a project or task.
Example: "After years of working independently, she decided to reconnect with a former collaborator to explore new ideas."
Alternatives: "an ex-colleague" or "a past associate".
The orchestral arrangements are by Claus Ogerman, a former collaborator of Antonio Carlos Jobim.
It's photographed by Jong Lin, a former collaborator of Ang Lee.
"Mike has no tolerance for failure," says a former collaborator who tried to rally him after May's departure.
Robert Trivers, an eminent biologist at Rutgers and a former collaborator with Wilson, wrote a strongly worded personal e-mail to Nowak.
The bane of the Nixon administration has become, in the words of Scott Armstrong, a former collaborator, "the father-confessor to many senior officials".
Frank Wilson, a former collaborator with Jonzi-D and Robert Hylton's Urban Classicism, who turns up in Into the Hoods as the Landlord, reckons it's about time hip-hop moved in the direction of the West End.
She's an immensely generous spirited interviewer, which means that she's as effective at getting the goods as any former collaborator.
Earlier this year, Kill Them With Colour transitioned from a two-man act to a solo project, as former collaborator Jason Carr moved on to pursue a career in long-term care.
The author beat a shortlist including his former collaborator Terry Pratchett with Nation, Philip Reeve's Fever Crumb and Patrick Ness's The Ask and the Answer to take the prize, which is judged by 12 children's librarians.
This being an occasion for nostalgia, former collaborator Etienne Daho, who could look no more French if he cycled on stage wearing a striped jumper, murmurs in Gallic fashion over Jungle Pulse.
Sotheby's, its arch-rival (and former collaborator in a price-fixing scandal), saw its sales rise by a similar percentage, to $6bn.
