Put at risk adopting a measure such as this (8)
I believe the answer is:
imperial
'measure such as this' is the definition.
(as in imperial measurements)
'put at risk adopting a' is the wordplay.
'put at risk' becomes 'imperil' (I've seen this before).
'adopting' is an insertion indicator.
'imperil' going around 'a' is 'IMPERIAL'.
(Other definitions for imperial that I've seen before include "measure" , "Like some rulers" , "Magnificent; small pointed beard" , "Related to empire" , "Regal - type of beard" .)