Different wire in separate rocket, say (8)
I believe the answer is:
firework
'rocket say' is the definition.
(rocket is a kind of firework)
'different wire in separate' is the wordplay.
'different' is an anagram indicator (letters placed in a different order).
'in' is an insertion indicator.
'separate' becomes 'fork' (synonyms).
'wire' is an anagram of 'irew'.
'irew' going into 'fork' is 'FIREWORK'.
(Other definitions for firework that I've seen before include "rocket" , "Pyrotechnic device" , "fountain, say" , "Banger, for example" , "Colourful incendiary device used for entertainment" .)