Need solid vessel (8)
I believe the answer is:
hardship
'need' is the definition.
(I've seen this before)
'solid vessel' is the wordplay.
'solid' becomes 'hard' (similar in meaning).
'vessel' becomes 'ship' (ship is a kind of vessel).
'hard'+'ship'='HARDSHIP'
(Other definitions for hardship that I've seen before include "Physical suffering is a tough vessel" , "Difficulty, vicissitude" , "State of misfortune or affliction" , "Lack of life's necessities, a tough time" , "Difficult circumstances" .)