Go up, up, up in the old Russian secret police (4)
I believe the answer is:
ogpu
'russian secret police' is the definition.
(I've seen this in another clue)
'go up up up' is the wordplay.
'up' is a reversal indicator (in down clue: letters go upwards).
'up' is a reversal indicator (in down clue: letters go upwards).
'go' reversed gives 'og'.
'up' backwards is 'pu'.
'og'+'pu'='OGPU'
'in the old' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for ogpu that I've seen before include "Soviet secret police, 1923-34" , "Russian secret police nineteen twenty two to nineteen thirty four; go up (anag.)" .)