The crossword solution for the term SUFFIX WITH SONNET is 'EER', which is a three-letter suffix. This suffix is commonly used to denote a person who performs a certain action or has a certain quality. For example, a 'TEACHER' is someone who teaches, and so the suffix '-er' is added to the word 'TEACH' to create the word 'TEACHER'. Similarly, a 'POET' is someone who writes poetry, and so the suffix '-er' is added to the word 'POET' to create the word 'POET'. In this case, the suffix '-er' is added to the word 'SONNET' to create the word 'sonneter', which is someone who writes sonnets.