Aquarium commercial including introduction from Rick Stein? (7)
I believe the answer is:
tankard
'stein?' is the definition.
(I've seen this in another clue)
'aquarium commercial including introduction from rick' is the wordplay.
'aquarium' becomes 'tank' (I've seen this in another clue).
'commercial' becomes 'ad' (abbreviation for advertisement).
'including' is an insertion indicator.
'introduction from' says to take the initial letters.
The first letter of 'rick' is 'r'.
'ad' going around 'r' is 'ard'.
'tank'+'ard'='TANKARD'
(Other definitions for tankard that I've seen before include "A drinking mug with handle" , "Mug-like drinking vessel" , "something to drink from" , "Beer-mug" , "Tall beer mug" .)