Peaceful place lacking bitter (4)
I believe the answer is:
acid
'bitter' is the definition.
(acid can mean bitter-tasting)
'peaceful place lacking' is the wordplay.
'peaceful' becomes 'placid' (I've seen this in another clue).
'place' becomes 'pl' (abbreviation used in postal addresses).
'lacking' suggests deleting specific letters.
'placid' with 'pl' taken away is 'ACID'.
(Other definitions for acid that I've seen before include "Sarcastic - tart" , "Bitter or sour" , "Acerbic" , "Sour - vitriolic" , "Sour to the taste" .)