Dread is maybe revealing horror (6)
I believe the answer is:
dismay
'horror' is the definition.
(thesaurus)
'dread is maybe revealing' is the wordplay.
'revealing' indicates the answer is hidden within the clue.
'DISMAY' can be found hidden inside 'dread is maybe'.
(Other definitions for dismay that I've seen before include "trouble" , "Consternation, discouragement" , "Alarm, distress" , "Fill with consternation" , "Fill with apprehension" .)