Time to leave desolate island (4)
I believe the answer is:
sark
'island' is the definition.
(I've seen this before)
'time to leave desolate' is the wordplay.
'time' becomes 't' (abbreviation).
'to leave' indicates named letters should be taken away.
'desolate' becomes 'stark' (I've seen this in another clue).
'stark' with 't' taken out is 'SARK'.
(Other definitions for sark that I've seen before include "shirt from Scotland" , "English Channel isle" , "Scottish shirt; island" , "One of Channel Isles" , "Island near Guernsey" .)