Minor deviation, hiccup (4)
I believe the answer is:
blip
I believe this clue is a double definition.
'minor deviation' is the first definition.
(I've seen this in another clue)
'hiccup' is the second definition.
(I've seen this before)
(Other definitions for blip that I've seen before include "Minor (and temporary) deviation from trend" , "Glitch" , "Short-lived deviation" , "Temporary setback - short high-pitched sound" , "Radar image; minor deviation" .)