Level-headed (4)
'level-headed' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for realistic that I've seen before include "Practicable" , "It is clear, being practical and sensible" , "Pragmatic" , "Facing facts, as it is clear" , "accurate picture" .)
(Other definitions for grounded that I've seen before include "Not allowed to fly" , "Prevented from flying" , "Based; forbidden to fly" , "Earthed" , "prevented from leaving home" .)
'level-headed' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sane that I've seen before include "Mentally healthy" , "Rational" , "In full possession of mental faculties" , "Normal" , "Right-minded" .)