Luncheon's not so awkward in this submarine route (7)
I believe the answer is:
chunnel
'this submarine route' is the definition.
The definition suggests a singular noun which matches the answer.
'luncheon's not so awkward' is the wordplay.
'not' is a deletion indicator.
'awkward' indicates anagramming the letters.
'luncheons' with 'so' taken out is 'lunchen'.
'lunchen' is an anagram of 'CHUNNEL'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for chunnel that I've seen before include "Railway passage between England and France" , "Kent/Pas-de-Calais link" , "Anglo-French link" .)