The most common and most likely answer to this crossword clue is the 7 letter word HICCUPS
H
I
C
C
U
P
S
More clues leading to the result HICCUPS
Buddy explains!

The straight part
We know that "reflexive spasms" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case reflexive spasms = hiccups.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 HICCUPS mean?
HICCUPS noun- A spasm of the diaphragm, or the resulting sound.
- (by extension) Any spasm or sudden change.
- A minor setback.
- To produce a hiccup; have the hiccups.
- To say with a hiccup.
- To produce an abortive sound like a hiccup.
- (usually with "the") The condition of having the spasms of hiccupping.