The most common and most likely answer to this crossword clue is the 10 letter word ANASTOMOSE
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The straight part
We know that "Intercommunicate" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case intercommunicate = anastomose.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ANASTOMOSE mean?
ANASTOMOSE verb- (of streams and rivers, blood vessels, etc) To join (two or more things) by anastomosis, to interconnect forming a network.
- (of rivers, blood vessels, etc) To join by anastomosis.
- Joined or run together. Interconnected
- (of rivers, etc) Joined or run together, ramified, interconnected