Check container vessel (5)
I believe the answer is:
churn
'vessel' is the definition.
(churn is a kind of vessel)
'check container' is the wordplay.
'check' becomes 'ch' (I've seen this in other clues).
'container' becomes 'urn' (urn is a kind of container).
'ch'+'urn'='CHURN'
(Other definitions for churn that I've seen before include "Stir violently - to make butter?" , "Butter-making machine" , "Heave" , "in which butter's made" , "Machine in which milk is beaten to make butter" .)