clut·ter / ˈklətər/ • n. a collection of things lying about in an untidy mass: the attic is full of clutter. ∎  [in sing.] an untidy state: the room was in a clutter of smelly untidiness.• v. [tr.] crowd (something) untidily; fill with clutter: his apartment was cluttered with paintings and antiques luggage cluttered up the hallway.

clutter †clotted mass XVI; confused mass or crowd, noisy turmoil, confused noise XVII. var. of †clotter (XIV), †clodder (XV), f. CLOT, CLOD; see -ER 4; assoc. to some extent with cluster and clatter.
So as vb. XVI.

Clutter

a confused collection; a clotted mass; a crowded and confused group; a collection. See also clowder.

Examples: clutter of bodies, 1674; of business, 1649; of cats; of citations, 1666; of consonants, 1791; of narrow crooked, dark, and dirty lanes, 1792; of drops against the glass, 1841; of spiders; of thick and deep grass, 1670.