During hostilities Democrat reveals secret (6)
I believe the answer is:
inward
'secret' is the definition.
(thesaurus)
'during hostilities democrat' is the wordplay.
'during' becomes 'in' (I've seen this in other clues).
'hostilities' becomes 'war' (I've seen this before).
'democrat' becomes 'd'.
'in'+'war'+'d'='INWARD'
'reveals' acts as a link.
(Other definitions for inward that I've seen before include "Towards the centre" , "In the mind or spirit, not outside" , "Formerly private" , "Existing in the mind - to the centre" , "Situated on the inside" .)