American shields companion's PIN, for example (7)

I believe the answer is:
acronym
'pin for example' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'american shields companion's' is the wordplay.
'american' becomes 'Am' (abbreviation in some contexts).
'shields' means one lot of letters goes inside another (shield can mean goes around or covers).
'companion' becomes 'crony' (I've seen this before).
'am' enclosing 'crony' is 'ACRONYM'.
Can you help me to learn more?
(Other definitions for acronym that I've seen before include "Perhaps NATO" , "NATO, for example" , "eg Ernie; radar" , "Word like laser or Aids" , "My acorn may generate a new word from first letters" .)
