Grabbed sheets to cover bunks (4)
I believe the answer is:
beds
'bunks' is the definition.
(I've seen this before)
'grabbed sheets to cover' is the wordplay.
'to cover' indicates a hidden word (I've seen 'covered' mean this (the answer is covered up by the clue)).
'BEDS' is hidden in the letters of 'grabbed sheets'.
(Other definitions for beds that I've seen before include "area that includes Luton" , "County (abbr.); sleeping places" , "furniture items?" , "Pieces of furniture" , "borders" .)