Keen, agree to dance (5)
I believe the answer is:
eager
'keen' is the definition.
(thesaurus)
'agree to dance' is the wordplay.
'to dance' indicates an anagram (letters must dance around).
'agree' is an anagram of 'EAGER'.
(Other definitions for eager that I've seen before include "Anxious" , "really keen" , "Keen - enthusiastic" , "passionate" , "Zealous" .)