Yarn going round black board (5)
I believe the answer is:
table
'board' is the definition.
(synonyms)
'yarn going round black' is the wordplay.
'yarn' becomes 'tale' (synonyms).
'going round' means one lot of letters goes inside another.
'black' becomes 'b' (as in pencil classifications).
'tale' enclosing 'b' is 'TABLE'.
(Other definitions for table that I've seen before include "Horizontal furniture" , "put on the agenda" , "Put forward for formal discussion" , "Submit for consideration" , "Array of data" .)