Become extremely sincere and olde-worlde on tranquillisers (7)
I believe the answer is:
sedated
'become extremely sincere and olde-worlde' is the definition.
I can't tell whether this defines the answer.
'on tranquillisers' is the wordplay.
I cannot really understand how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sedated that I've seen before include "Under the influence of drugs" , "Drugged" , "kept calm" , "Given calming drugs" , "Tranquillized" .)