Recipe containing an obscene thing served on board? (6,4)
I believe the answer is:
danish blue
'thing served on board?' is the definition.
(a cheese that might appear on a cheeseboard)
'recipe containing an obscene' is the wordplay.
'recipe' becomes 'dish'.
'containing' means one lot of letters goes inside another.
'obscene' becomes 'blue'.
'dish' enclosing 'an' is 'danish'.
'danish'+'blue'='DANISH BLUE'
(Other definitions for danish blue that I've seen before include "possibly crackers with it" , "served up on board?" .)