'To throw down the glove' definitions:

Definition of 'To throw down the glove'

From: GCIDE

Glove \Glove\ (gl[u^]v), n. [OE. glove, glofe, AS. gl[=o]f; akin to Icel. gl[=o]fi, cf. Goth. l[=o]fa palm of the hand, Icel. l[=o]fi.] [1913 Webster]
1. A cover for the hand, or for the hand and wrist, with a separate sheath for each finger. The latter characteristic distinguishes the glove from the mitten. [1913 Webster]
2. A boxing glove. [1913 Webster]
Boxing glove. See under Boxing.
Glove fight, a pugilistic contest in which the fighters wear boxing gloves.
Glove money or Glove silver. (a) A tip or gratuity to servants, professedly to buy gloves with. (b) (Eng. Law.) A reward given to officers of courts; also, a fee given by the sheriff of a county to the clerk of assize and judge's officers, when there are no offenders to be executed.
Glove sponge (Zool.), a fine and soft variety of commercial sponges (Spongia officinalis).
To be hand and glove with, to be intimately associated or on good terms with. "Hand and glove with traitors." --J. H. Newman.
To handle without gloves, to treat without reserve or tenderness; to deal roughly with. [Colloq.]
To take up the glove, to accept a challenge or adopt a quarrel.
To throw down the glove, to challenge to combat. [1913 Webster]