Straight, without deviation (6)
I believe the answer is:
direct
I believe this is a double definition.
'straight' is the first definition.
(I know that straight can be written as direct)
'without deviation' is the second definition.
(I've seen this before)
(Other definitions for direct that I've seen before include "Straight, without diversion" , "Guide with credit" , "Creepy-crawly" , "Moving without changing direction or stopping" , "Following the quickest and shortest path" .)