British merge involved taking turn in vessel (4,3)
I believe the answer is:
beer mug
'vessel' is the definition.
(I know that beer mug is a type of mug)
'british merge involved taking turn' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'involved' is an anagram indicator (involved can mean confusing or complex).
'taking' is an insertion indicator.
'turn' becomes 'u' (a 'U-turn' is a kind of turn).
'merge' with letters rearranged gives 'eermg'.
'eermg' going around 'u' is 'eermug'.
'b'+'eermug'='BEER-MUG'
'in' is the link.
(Other definitions for beer mug that I've seen before include "Drink container" , "Cup for best" , "Stein or tankard" , "glass" , "drinking vessel" .)