Large duck with bill for storing of milk (7)
I believe the answer is:
lacteal
'of milk' is the definition.
(lacteal means relating to milk)
'large duck with bill' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'duck' becomes 'teal' (teal is a type of duck).
'with' says to put letters next to each other.
'bill' becomes 'ac' (abbreviation for account).
'teal' put after 'ac' is 'acteal'.
'l'+'acteal'='LACTEAL'
'for storing' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
(Other definitions for lacteal that I've seen before include "Milky resin" , "Milk-like; pertaining to milk" .)