Measurement system (6)
I believe the answer is:
metric
'measurement system' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for metric that I've seen before include "Consisting of verses; pertaining to one system of measurement" , "Successor to imperial (system)" , "Like some feet" , "Of modern measuring units" , "System using litre and gram as units" .)