Yes, it would be fine to inject one service into the constructor of another. However, you might want to consider creating an interface for OrganisationService and having your AgreementService depend upon that abstraction, instead.
Another approach would be to create a new service with dependencies on both AgreementService and OrganisationService, and have that new service carry out the responsibility. The new service would of course be injected into your controller.
For guidance, consider whether having it all under AgreementService would violate the Single Responsibility Principle and/or Interface Segregation Principle. If so, make a new service.