One rumbling method at heart even more inferior, as it were? (9)
I believe the answer is:
thunderer
'one rumbling method' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'heart even more inferior as it were?' is the wordplay.
I cannot really understand how this works, but
'heart' could be 'h' (card game abbreviation) and 'h' is located in the answer.
'inferior' could be 'under' (I've seen this before) and 'under' is found in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'at' acts as a link.
Can you help me to learn more?
(Other definitions for thunderer that I've seen before include "The -, nickname for The Times" , "Jupiter, say" , "Our paper" , "Loud protester" .)