Quiet journalists wearing glasses start to rattle tyrant (9)
I believe the answer is:
oppressor
'tyrant' is the definition.
(I've seen this before)
'quiet journalists wearing glasses start to rattle' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'journalists' becomes 'press' (the press can mean the newspaper industry).
'wearing' means one lot of letters goes inside another.
'glasses' becomes 'OO' (OO looks like spectacles).
'start to' says to take the initial letters.
The initial letter of 'rattle' is 'r'.
'p'+'press'='ppress'
'ppress' inserted inside 'oo' is 'oppresso'.
'oppresso'+'r'='OPPRESSOR'
(Other definitions for oppressor that I've seen before include "One tyrannises" , "Proposers for one who persecutes" , "Persecutor of proposers" , "One who keeps another in subjection" , "Despot" .)