Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
cruscŭlum, i, n. dim. [crus], a small leg or shank, Plaut. Fragm. ap. Paul. ex Fest. p. 52, 20 Müll.; cf. Paul. ib. p. 53, 1 ib.