This vessel can't rise awkwardly (8)
I believe the answer is:
canister
'this vessel' is the definition.
(I've seen this before)
'can't rise awkwardly' is the wordplay.
'awkwardly' indicates anagramming the letters.
'cant'+'rise'='cantrise'
'cantrise' with letters rearranged gives 'CANISTER'.
(Other definitions for canister that I've seen before include "Jar (of e.g. tea, sugar)" , "Metal food container" , "Small metal container" , "Tea-caddy" , "Cylindrical container" .)