Existing image deraining models struggle to handle complex real-world scenarios with rain-mist coupled degradation. The core challenge stems from the high visual similarity and spatial coupling between rain streaks and mist, making it difficult to accurately model their joint degradation patterns. Consequently, both specialized deraining models and all-in-one models for multiple degradations are ineffective in rain-mist coexistence scenarios. To address these challenges, we propose a novel Rain-Mist Removal (RMR) framework. It effectively utilizes single degradation priors from existing deraining and dehazing datasets to model the joint degradation, thereby achieving effective rain streak removal while preserving background structures obscured by mist. To enhance the generalization to real-world scenarios, we leverage text prompts trained in the CLIP perceptual space to drive the generated results toward real samples. Extensive experiments demonstrate that the proposed RMR outperforms state-of-the-art methods in rain-mist coexistence scenarios.