Specific — fast (7)
I believe the answer is:
express
This clue is a double definition.
'specific' is the first definition.
(e.g. specific instructions)
'fast' is the second definition.
(I've seen this before)
(Other definitions for express that I've seen before include "haste" , "Rapid" , "set forth" , "High-speed; specific" , "Quickly" .)