Briefly fume before violent rumble (3,7)
I believe the answer is:
see through
'rumble' is the definition.
(both can mean to realise the truth about someone)
'briefly fume before violent' is the wordplay.
'briefly' means to remove the last letter.
'fume' becomes 'seethe' (I've seen this before).
'before violent' becomes 'rough' (I've seen this in another clue. I am not sure about the 'before' bit.).
'seethe' with its last letter taken off is 'seeth'.
'seeth'+'rough'='SEE-THROUGH'
Can you help me to learn more?
(Other definitions for see through that I've seen before include "sheer?" , "Stay to the end" , "Get to the bottom of" , "Perceive the true nature of" , "thin clothes" .)