Highland Browns are usually considered to be septs of Lamont or Macmillan... that said, there has recently been an attempt to create a "Clan Brown" complete with a soit-disant chief and "clan" tartan. The reality seems to be that the name "Brown" as it occurs through out Scotland probably originally referred to hair or eye colour (as in Angus with brown hair, etc.). In the lowlands the name is associated with Sir David le Brun, who was present at the laying of the foundation of the Abbey of Holyrood House in 1128.

If you are looking for a "clan connection" I'd suggest you might want to choose between Lamont or Macmillan, both of which accept Browns as a recognized sept, and both of which are found in Argyll.