Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* angustĭclāvĭus, a, um, adj. [angustus-clavus], wearing a narrow (purple) stripe; an epithet of a plebeian tribune, who, as a plebeian, could wear only a narrow stripe of purple on his tunic (while the tribune from the nobility had a broad stripe, v. laticlavius), Suet. Oth. 10.