Frowning in consternation (5)
I believe the answer is:
stern
'frowning' is the definition.
(thesaurus)
'in consternation' is the wordplay.
'in' indicates the answer is hidden within the clue.
'STERN' can be found hidden inside 'consternation'.
(Other definitions for stern that I've seen before include "Unpleasantly serious" , "at the back of the galley!" , "Severe part of the ship?" , "Severe -- back of boat" , "Ship's rear" .)