Minor hiccup (4)
I believe the answer is:
blip
'minor hiccup' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for blip that I've seen before include "shows up on radar screen" , "Momentary deviation" , "Temporary exception" , "Short-lived deviation" , "Minor (and temporary) deviation from trend" .)