In protest against Turberville's mistreatment, the Welsh nobleman Llywelyn Bren and his supporters launched a surprise attack on 28 January 1316, and besieged Caerphilly Castle, which successfully held out under the command of "The lady of Clare" (almost certainly Eleanor) and a small garrison until relieved by Sir William Montacute on 12 March 1316.

Eleanor's fortunes changed drastically after the invasion in September 1326 of Edward's estranged wife, Queen Isabella, and her lover, Roger Mortimer, who overthrew the King; two months later, her husband Hugh was convicted of high treason and subsequently hanged, drawn, and quartered.

The abduction may in fact have been an elopement; in any case, Eleanor's lands were seized by King Edward III, and the couple's arrest was ordered.

In January 1330 she was released and pardoned after agreeing to sign away the most valuable part of her share of the lucrative Clare inheritance to the crown.

Within the year, however, the young future King Edward III (Eleanor's first cousin) overthrew Queen Isabella's paramour, Roger Mortimer, 1st Earl of March, and had him executed.

She petitioned Edward III for the restoration of her lands, claiming that she had signed them away after being threatened by Roger Mortimer that she would never be freed if she did not.

Eleanor is a supporting character in Les Rois maudits (The Accursed Kings), a series of French historical novels by Maurice Druon.

Eleanor features in the 1975/1976 two-part novel, Feudal Family: The De Clares of Gloucester, by Edith Beadle Brouwer.