The term 'knocks flat' can be solved by two crossword solutions: PASTES (6 letters) and DECKS (5 letters). PASTES is a verb meaning to spread a thick, sticky substance over a surface. It is often used in cooking or crafting. DECKS is a noun referring to a flat surface, usually made of wood, that is used for outdoor activities such as lounging or entertaining. Both words are related to the term 'knocks flat' because they both refer to a flat surface.