can anyone identify?

[Ellerian]

 

[DirtMechanic]

I will hazard a guess. It may be a Large Num-Num or some variant. Also called a Natal Plum.

https://en.m.wikipedia.org/wiki/Carissa_macrocarpa

 

[Marck]

Yes I concur, Natal Plum (Carissa macrocarpa), in the Dogbane Family (Apocynaceae) native to southern Africa.

It is strange biting into a fruit with milky juice, especially from a Family renowned for toxic plants, but Natal Plums are sweet and delicious.