Conservative opens my beer in a rounded vessel (7)
I believe the answer is:
coracle
'rounded vessel' is the definition.
'coracle' can be an answer for 'vessel' (coracle is a kind of vessel). I'm not certain of the 'rounded' bit.
'conservative opens my beer' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'opens' means one lot of letters goes inside another (some letters open a gap in others).
'my' becomes 'cor' (both are expressions of surprise).
'beer' becomes 'ale' (type of beer).
'cor'+'ale'='corale'
'c' inserted within 'corale' is 'CORACLE'.
'in a' acts as a link.
Can you help me to learn more?
(Other definitions for coracle that I've seen before include "Small rowing boat of wicker and hide" , "Small round boat of hides stretched over a wicker frame" , "craft" , "Small primitive boat" , "Welsh wickerwork boat" .)