Dependable engineers exposed to risk (8)
I believe the answer is:
reliable
'dependable' is the definition.
('reliable' can be a synonym of 'dependable')
'engineers exposed to risk' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'exposed to risk' becomes 'liable' (I've seen this before).
're'+'liable'='RELIABLE'
(Other definitions for reliable that I've seen before include "Dependable, honest" , "worthy of trust" , "Dependable, can be trusted" , "Trusty" , "Able to be depended on" .)