Open tavern: initially landlord in charge (6)
I believe the answer is:
public
'open' is the definition.
(similar in meaning)
'tavern initially landlord in charge' is the wordplay.
'tavern' becomes 'pub' (pub is a kind of tavern).
'initially' indicates taking the first letters.
'in charge' becomes 'ic' (abbreviation for 'in charge').
The first letter of 'landlord' is 'l'.
'pub'+'l'+'ic'='PUBLIC'
(Other definitions for public that I've seen before include "General - population" , "Strangely enough, these English schools are not" , "Serving the people" , "State-owned; in the open" , "This house is licensed to sell alcohol" .)