Spread of cloth held up by sailor (9)
I believe the answer is:
margarine
'up by sailor' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'spread of cloth held' is the wordplay.
'spread' becomes 'marge' (marge is a kind of spread).
'of cloth' becomes 'arin' (I can't explain this - if you can you should believe this answer much more).
'held' indicates putting letters inside.
'marge' placed around 'arin' is 'MARGARINE'.
Can you help me to learn more?
(Other definitions for margarine that I've seen before include "Is Ma angrier at this spread?" , "Reg and Marian make a butter substitute" , "Substitute spread for butter" , "F [FAT]" , "Fat-based butter substitute" .)