Crease the last of the clean sheets (5)
I believe the answer is:
linen
'sheets' is the definition.
(I've seen this before)
'crease the last of the clean' is the wordplay.
'crease' becomes 'line' (synonyms).
'the last of' suggests the final letters.
The last letter of 'clean' is 'n'.
'line'+'n'='LINEN'
(Other definitions for linen that I've seen before include "Lenin (anag) -- fabric" , "Such paper" , "Flaxen cloth" , "Flax textile" , "fabricated? This is" .)