Perch (5)
'perch' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for roost that I've seen before include "Place for sleeping birds" , "suitable sleeping-place" , "(Bird) settle for sleep" , "Rest on a perch" , "Bird's night-time perch" .)
'perch' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sit that I've seen before include "Take a chair" , "Perch" , "as magistrates do" , "Be seated" , "I sell badly the cotton yarn" .)