The entry in Turner:
5543 *ḍākka1 ʻ robber, robbery ʼ. [Ac. to W.Wüst RM 3, 33, with *ṭhakk -- 2, ← non -- Aryan adaptation of śāka -- ]
P. ḍākā m. ʻ robbery, band of robbers ʼ, ḍākū m. ʻ robber ʼ; N. ḍāku, ḍã̄kā, ˚ku, ḍakait ʻ robber ʼ, A. B. ḍāku, ḍakāit, Or. ḍāku, ḍã̄ku, ḍakāita, Mth. ḍākū, ḍakait; H. ḍākā, m. ʻ robbery, band of robbers ʼ, ḍākū, ḍã̄kū, ḍakait m. ʻ robber ʼ; G. ḍākɔ m. ʻ attack by robbers ʼ; M. ḍã̄kā m. ʻ band of robbers, attack by robbers ʼ; -- G. ḍākũ ʻ dishonoured ʼ, ḍākiyũ, ḍākṇũ ʻ wicked ʼ (or < ḍākínī -- ).
That is: from a hypothetical Sanskrit *ḍākka. Not perhaps enormously useful.