Manchester measurement (5)
I believe the answer is:
metre
'manchester measurement' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for metre that I've seen before include "39.37 inches" , "Characteristic of feet" , "Approx 39 inches" , "Beat pattern (mus.)" , "three and a bit of a fourth" .)