The term 'FUNDAMENTAL INGREDIENT' can be broken down into two words, with the crossword solution for the first word being 'BASIS'. The word 'BASIS' is defined as a fundamental principle or starting point, and is often used to describe the foundation of something. In this context, it could refer to the essential components that make up a particular recipe or dish. Therefore, the phrase 'FUNDAMENTAL INGREDIENT' could be interpreted as the key elements that are necessary for a successful outcome.