Runaway tyrannical speech about a politician (7)

I believe the answer is:
rampant
'runaway' is the definition.
(I've seen this in another clue)
'tyrannical speech about a politician' is the wordplay.
'tyrannical speech' becomes 'rant' (rant is a kind of speech. I am not sure about the 'tyrannical' bit.).
'about' indicates putting letters inside.
'politician' becomes 'MP' (Member of Parliament).
'a'+'mp'='amp'
'rant' enclosing 'amp' is 'RAMPANT'.
Can you help me to learn more?
(Other definitions for rampant that I've seen before include "Unchecked - standing up on hind legs" , "Flourishing excessively as disease may be" , "Mantrap (anag) - unrestrained" , "Showing unchecked growth" , "Unrestrained and violent" .)
