Distinguish from constellation (4)
I believe the answer is:
tell
'distinguish' is the definition.
(synonyms)
'from constellation' is the wordplay.
'from' says the answer is hidden in the clue.
'TELL' can be found hidden inside 'constellation'.
(Other definitions for tell that I've seen before include "Relate (a story)" , "William ..., skilled Swiss archer" , "Narrate; inform" , "Relate; Swiss hero" , "Count - recount" .)