Some salad dressing seen at 16 (7)
I believe the answer is:
address
'16' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'some salad dressing seen' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'ADDRESS' can be found hidden inside 'salad dressing seen'.
'at' is the link.
(Other definitions for address that I've seen before include "Form of identification for building" , "Where one lives" , "Attend" , "directions in window" , "Discourse" .)