Weight of intonation? (3)
I believe the answer is:
ton
'weight' is the definition.
(ton is a kind of weight)
'of intonation?' is the wordplay.
'of' indicates the answer is hidden within the clue.
'TON' can be found hidden inside 'intonation'.
(Other definitions for ton that I've seen before include "Imperial unit of weight" , "20cwt" , "100 mph, runs, etc" , "Speed" , "Two thousand, two hundred and forty lbs avoirdupois" .)