What may be blue in South Kentucky (3)
I believe the answer is:
sky
'what may be blue' is the definition.
'south kentucky' is the wordplay.
'south' becomes 's' ('S' can be a synonym of 'south').
'kentucky' becomes 'ky'.
's'+'ky'='SKY'
'in' is the link.
(Other definitions for sky that I've seen before include "Hit high into the air" , "Heavens above!" , "Orbiting space-station" , "Firmament" , "Outer space viewed from earth" .)