Sort of bomb set off in nice yard (10)
I believe the answer is:
incendiary
'sort of bomb' is the definition.
'set off in nice yard' is the wordplay.
'set off' indicates anagramming the letters.
'in'+'nice'+'yard'='inniceyard'
'inniceyard' is an anagram of 'INCENDIARY'.
(Other definitions for incendiary that I've seen before include "of a provocative nature" , "bomb" , "Inciting riot" , "Likely to stir up trouble" , "tending to stir up trouble" .)