Squeeze out food store with extremely fast mail (7,8)
I believe the answer is:
'fast mail' is the definition.
The definition suggests a singular noun which matches the answer.
'squeeze out food store with extremely' is the wordplay.
'squeeze out' becomes 'express' (I am not sure about this - if you are sure you should believe this answer much more).
'food store' becomes 'deli' (I've seen this in other clues).
'with' means one lot of letters go next to another.
'extremely' becomes 'very' (very can mean extremely or considerably).
Can you help me to learn more?