The most common and most likely answer to this crossword clue is the 8 letter word REFLEXES
I've seen this crossword clue in The Daily Telegraph
R
E
F
L
E
X
E
S
More clues leading to the result REFLEXES
Buddy explains!
The straight part
We know that "Automatic responses" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case automatic responses = reflexes.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 REFLEXES mean?
REFLEXES noun- An automatic response to a simple stimulus which does not require mental processing.
- The descendant of an earlier language element, such as a word or phoneme, in a daughter language.
- The descendant of anything from an earlier time, such as a cultural myth.
- Reflection or an image produced by reflection. The light reflected from an illuminated surface to one in shade.