The Collaborative International Dictionary of English v.0.48:

Del credere \Del` cred"er*e\ [It., of belief or trust.]
   (Mercantile Law)
   An agreement by which an agent or factor, in consideration of
   an additional premium or commission (called a del credere
   commission), engages, when he sells goods on credit, to
   insure, warrant, or guarantee to his principal the solvency
   of the purchaser, the engagement of the factor being to pay
   the debt himself if it is not punctually discharged by the
   buyer when it becomes due.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

DEL CREDERE, contracts. A del credere commission is one under which the
agent, in consideration of an additional premium, engages to insure to his
principal not only the solvency of the debtor, but the punctual discharge of
the debt; and he is liable, in the first instance, without any demand from
the debtor. 6 Bro. P. C. 287; Beawes, 429; 1 T. Rep. 112; Paley on Agency,
39.
     2. If the agent receive the amount of sales, and remit the amount to
the principal by a bill of exchange, he is not liable if it should be
protested. 2 W. C. C. R. 378. See, also, Com. Dig. Merchant, B; 4 M. & S.
574.