Diner wolfing last of rucola? Never bolt down rocket here (8)
I believe the answer is:
launcher
'never bolt down rocket here' is the definition.
(a launcher should release rockets)
'diner wolfing last of rucola?' is the wordplay.
'diner' becomes 'luncher'.
'wolfing' means one lot of letters goes inside another (wolf can mean to eat or swallow).
'last of' suggests the final letters.
The last letter of 'rucola' is 'a'.
'luncher' enclosing 'a' is 'LAUNCHER'.
(Other definitions for launcher that I've seen before include "starter" , "Missile firer" , "Rocket firer" .)