Constellation critter (4)
I believe the answer is:
ursa
'constellation critter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ursa that I've seen before include "'Major and Minor, constellations (4)'" , "(& 19 across) Plough constellation" , "- Major, - Minor, prominent constellations" , "(In the sky) Major or Minor" , "__ Minor, the Little Bear" .)