Obs. [Orig. a Flemish word of the wool-trade: Kilian, 1598, has ‘klacken detergere lutum, used in Fland. Brug., for kladden, afkladden abstergere sordes, detergere lutum, detergere vestem peniculo, stringere,’ also ‘klacke Fland. = kladde macula lutosa, lutum vestibus hærens, nota cænosa,’ a dirty mark. Cf. Ger. klacke spot of dirt, in Grimm. Hence med.L. claccāre: see Du Cange.] trans. To remove the dirty parts, esp. the tarry mark or ‘buist’ from (a fleece of wool). (Cf. CLAG v. 4.)
1429. Act 8 Hen. VI., xxii. Great hinderance commeth to the King in his Customes and Subsidies by them that doe clacke and force the good Woolles of the Realme.
[1472. in Rymer, Foedera, XI. 735. ‘Quod … lanas quascumque berdare, claccare, et mundare possint.’]
1485. Act 1 Hen. VII., c. 10 § 7. That the same Wolle shuld be as it was shorne and clene wounde, withoute any sortyng, barbyng or clakkyng.
1607. Cowell, Interpr., To clack wooll is to cut off the sheepes marke which maketh it to waigh less and yield less custom to the king.
1641. in Termes de la Ley, 60 b.
1726. in Dict. Rust. (ed. 3).
