Related Clues:

• Essential
• Requisite
• Called for
• Not optional
• Vital
• Required
• Indispensable
• Needed
• Indespensable, essential
• Indispensable, essentional
• Absolutely essential
• Essential, indispensable
• Essential, as scenery may be
• Essential or unavoidable
• You'd have to have this to make any recess of it