The most common and most likely answer to this crossword clue is the 8 letter word SYNAPSES
I've seen this crossword clue in The Guardian
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More clues leading to the result SYNAPSES
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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 SYNAPSES mean?
SYNAPSES noun- The junction between the terminal of a neuron and either another neuron or a muscle or gland cell, over which nerve impulses pass.
- To form a synapse.
- To undergo synapsis.
- The association of homologous maternal and paternal chromosomes during the initial part of meiosis.