Enthusiastic rally, regularly itch to get involved (7)
I believe the answer is:
lyrical
'enthusiastic' is the definition.
(thesaurus)
'rally regularly itch to get involved' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'to get involved' indicates an anagram.
The alternating letters of 'itch' are 'ic'.
'rally'+'ic'='rallyic'
'rallyic' anagrammed gives 'LYRICAL'.
(Other definitions for lyrical that I've seen before include "Song-like, imaginative or expressive" , "Highly enthusiastic" , "In poetic words, song-like" , "Enthusiastic - expressing the writer's feelings" , "Using poetic language, wax thus (7)" .)