Mixer (large) swallowed in drinking bout (7)
I believe the answer is:
Here is my best explanation:
'mixer' is the definition.
(blender is a kind of mixer)
'large swallowed in drinking bout' is the subsidiary indication.
'large' becomes 'l'.
'swallowed in' indicates putting letters inside.
'drinking bout' becomes 'bender' (I've seen this before).
'l' placed within 'bender' is 'blender'.
(Other definitions for blender that I've seen before include "Good mixer", "Liquidising device", "Kitchen machine", "Kitchen device", "food mixer", "Kitchen appliance", "Mixer", "Kitchen liquidiser", "Kitchen utensil" and "kitchen equipment".)