Clement arranged a binge at the Nag's Head (6)
I believe the answer is:
benign
'clement' is the definition.
(thesaurus)
'arranged a binge at the nag's head' is the wordplay.
'arranged' is an anagram indicator.
'at' is a charade indicator (letters next to each other).
'head' says to take the initial letters.
The first letter of 'nags' is 'n'.
'binge' anagrammed gives 'benig'.
'benig'+'n'='BENIGN'
(Other definitions for benign that I've seen before include "Salubrious" , "Mild and gentle, not malignant" , "Medically curable" , "Genial; not harmful" , "Liberal" .)