___ Major (constellation) (4)
I believe the answer is:
ursa
'major constellation' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ursa that I've seen before include "It's both major anf minor overhead" , "Major/Minor constellation" , "(and 11 across) Pole Star constellation" , "Latin for the Great Bear, . . . . Major" , "(& 19 across) Plough constellation" .)