clarify (v.)
early 14c., "make illustrious, make known," from Old French clarifiier "clarify, make clear, explain" (12c.), from Late Latin clarificare "to make clear," also "to glorify," from Latin clarificus "brilliant," from clarus "clear, distinct" (see clear (adj.)) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put").

Meaning "make clear, purify" is from early 15c. in English; intransitive sense of "grow or become clear" is from 1590s. Figurative sense of "to free from obscurity" is from 1823. Related: Clarified; clarifying.