Declare in a tavern (4)
I believe the answer is:
aver
'declare' is the definition.
(averring is a kind of declaring)
'in a tavern' is the wordplay.
'in' indicates the answer is hidden within the clue.
'AVER' is hidden within 'tavern'.
(Other definitions for aver that I've seen before include "'Affirm, assert (4)'" , "Declare or insist" , "Firmly maintain" , "claim" , "State decisively" .)