Shouts for a dairy product in a vessel (7)
I believe the answer is:
screams
'shouts' is the definition.
(I know this)
'dairy product in a vessel' is the wordplay.
'dairy product' becomes 'cream' (cream is a kind of dairy product).
'in' means one lot of letters goes inside another.
'a vessel' becomes 'SS' (prefix in ship names eg SS Great Britain).
'cream' going into 'ss' is 'SCREAMS'.
'for a' acts as a link.
(Other definitions for screams that I've seen before include "Shouts" , "Shrill cries" , "Yells" .)