Engineers track access (8)
I believe the answer is:
recourse
'access' is the definition.
(I've seen this before)
'engineers track' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'track' becomes 'course' ('course' can be a synonym of 'track'**).
're'+'course'='RECOURSE'
(Other definitions for recourse that I've seen before include "Help; option" , "Source of aid in troubles" , "Facility" , "one looked to for help?" , "Resource used to access help" .)