Gazing
'gazing' is the definition.
('stare' can be a synonym of 'gaze')
This is all the clue.
(Other definitions for staring that I've seen before include "Gawking" , "with eyes popping out" , "Looking with fixed gaze" , "See 11" , "Gazing long and fixedly at" .)
(Other definitions for navel that I've seen before include "regarded with complacency" , "Target of gaze" , "Scar on the stomach (for gazing at?)" , "Umbilicus" , "Something to contemplate" .)