Calculate silence about United's the end for Ole? (5)
I believe the answer is:
gauge
'calculate' is the definition.
(I know that gauge is a type of calculate)
'silence about united's the end for ole?' is the wordplay.
'silence' becomes 'gag' (gagging is a kind of silencing).
'about' indicates putting letters inside.
'united' becomes 'U' (abbreviation).
'the end for' says to take the final letters.
The last letter of 'ole' is 'e'.
'gag' enclosing 'u' is 'gaug'.
'gaug'+'e'='GAUGE'
(Other definitions for gauge that I've seen before include "Instrument to measure or test" , "Estimate, form judgement of" , "Adjudge" , "Distance between the rails of a railway track" , "Measuring instrument" .)