Get up late (3-2)
I believe the answer is:
lie-in
'get up late' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lie-in that I've seen before include "time spent with crossword, perhaps" , "Extended sleep" , "Extra snoozing" , "That extra hour or so in bed?" , "Extra time in bed" .)