Former NSW deputy premier Andrew Stoner says broadcaster Alan Jones defamed him by saying he "sold out" his farming constituency and gave favourable treatment to mining and resources companies in return for political donations to the Nationals.

But on Tuesday, lawyers for the top-rating 2GB breakfast host told the Supreme Court the term "sold out" is too ambiguous to be put to a jury.

Sued: Alan Jones. Credit:Wolter Peeters

Mr Stoner is suing Jones and Greens MP Jeremy Buckingham for defamation over a series of five broadcasts in June and August last year regarding the contentious issues of coal seam gas and coal mining in regional NSW.

Mr Stoner's barrister, Terence Tobin, QC, told Justice Lucy McCallum the broadcasts were "an extraordinarily virulent attack" on the former Nationals leader, who did not recontest his seat of Oxley at the March election.