The usual meaning of the Scottish word clishmaclaver (also clish-ma-claver, clishmaclaiver, clashmaclaver) is “idle talk, gossip, or empty chatter”. The OED says it was formed “apparently with allusion to clish-clash and claver, with echoic associations”, and finds it also used as a verb (“keep me clishmaclavering”).
Hiberno-English has the related short form clash “gossip” as both noun and verb. Terence Dolan notes clash in Sligo (“He’s an awful old clash”), while a century ago P. W. Joyce reported clashbag* “tale-bearer” or “busybody” in Armagh, Northern Ireland. There’s also the verb phrase clash on, meaning “tell tales on”.
In historian Brian Bonner’s short book A Society in Transition: Cameos of Irish Life I came across another, related sense of clishmaclaver, for a person who trades in such talk:
Every village has its vendor of local gossip, and Lagaguee was no exception. Thereabouts, the role was filled by a lady known as Cassie the Larker. The older people, when annoyed with her, called her a “clishmaclaver”, thereby expressing their contempt for her while indicating the Scottish influence on the speech of the area.
Clishmaclaver was the name of the Chambers Editors’ blog, but my encounters with the word have dwindled since that blog wound down.
The Irish phrase mar dhea, which I’ve described before as a sceptical interjection, also appears in Bonner’s book:
At eleven she made her way back to the Macklin Tavern, to join those who had gathered there to imbibe coffee or beer and exchange the gossip of the day. She took up her position among her own special cronies and in confidence, mar dhea, related the gist of the events of the early morning.
Here the phrase implies that her gossip was professedly just for her friends’ gratification, but that all parties understood it would soon be spread beyond those confines. Such is the clishmaclavering imperative.
* This -bag suffix remains popular in Ireland, as in the more recent ledgebag, etc.