One of the tympani tried with lid removed - strange (7)
I believe the answer is:
eardrum
'one of the tympani tried with lid' is the definition.
I can't judge whether this defines the answer.
'removed strange' is the wordplay.
'removed' becomes 'eard' (I can't justify this - if you can you should give a lot more credence to this answer).
'strange' becomes 'rum' (I've seen this before).
'eard'+'rum'='EARDRUM'
Can you help me to learn more?
(Other definitions for eardrum that I've seen before include "Listener partly" , "Auditory membrane" , "Tympanic membrane" , "One hears" , "Rude ram (anag.)" .)