Kangaroos need time to sleep (5)
I believe the answer is:
roost
'sleep' is the definition.
(for birds, to roost is to settle down to sleep)
'kangaroos need time' is the wordplay.
'kangaroos' becomes 'roos' (roo is short for kangaroo).
'need' is a charade indicator (letters next to each other).
'time' becomes 't' (abbreviation).
'roos'+'t'='ROOST'
'to' acts as a link.
(Other definitions for roost that I've seen before include "Perch where bird sleeps" , "Shetland tidal water" , "suitable sleeping-place" , "where fliers land" , "bed" .)