Distinguish from constellation (4)
I believe the answer is:
tell
'distinguish' is the definition.
(synonyms)
'from constellation' is the wordplay.
'from' indicates the answer is hidden within 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" .)