The most common and most likely answer to this crossword clue is the 8 letter word CATALYSE
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Buddy explains!
The straight part
We know that "influence in chemical make-up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case influence in chemical make-up = catalyse.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 CATALYSE mean?
CATALYSE verb- To bring about the catalysis of a chemical reaction.
- To accelerate a process.
- To inspire significantly by catalysis.