The most common and most likely answer to this crossword clue is the 8 letter word HEREWITH
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More clues leading to the result HEREWITH
Buddy explains!

The straight part
We know that "show indication of attachment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case show indication of attachment = herewith.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 HEREWITH mean?
HEREWITH adverb- With this; especially, with this letter or communication
- By this means
- In this way, hereby