It enables one to get an inside view of the post (6,6)
I believe the answer is:
letter opener
'view of the post' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'it enables one to get an' is the wordplay.
I cannot quite understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
'one' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
'get' could be 'let' (synonyms) and 'let' is present in the answer.
This explanation may well be incorrect...
'inside' acts as a link.
Can you help me to learn more?
(Other definitions for letter opener that I've seen before include "Paper knife" , "Knife for slitting envelopes" , "device for getting information from correspondents out" , "which could be dear, eg" , "Desktop tool" .)