Arcane section of army stick together (6)
I believe the answer is:
mystic
'arcane' is the definition.
(thesaurus)
'section of army stick together' is the wordplay.
'section of' indicates the answer is hidden within the clue.
'MYSTIC' is hidden within 'army stick together'.
(Other definitions for mystic that I've seen before include "Seer" , "Sixth sense believer?" , "One attaining high levels of spirituality" , "Paranormal, mysterious" , "Allegorical; sacredly obscure" .)