What is the suffix ('Pratyaya') present in the word 'निर्वासित' (Nirvasit)?

Suffixes are structural units added at the end of root words. The word 'निर्वासित' is formed by breaking down:
$$\text{Root Word }(निर्वास)+\text{Suffix }(इत)=\text{निर्वासित}$$

Therefore, the suffix present in the word is 'इत' (-it).