Hooter preceding the Queen's Cup (6)
I believe the answer is:
beaker
'cup' is the definition.
(beaker is a kind of cup)
'hooter preceding the queen's' is the wordplay.
'hooter' becomes 'beak' ('beak' can be a synonym of 'hooter').
'preceding' says to put letters next to each other.
'the queen' becomes 'er' (Elizabeth Regina).
'beak'+'er'='BEAKER'
(Other definitions for beaker that I've seen before include "Glass container in a laboratory" , "Drink container" , "Mug - large glass" , "Large drinking cup" , "Cup with a wide mouth" .)