Ring in extremely remarkable safe (7)
I believe the answer is:
resound
'ring' is the definition.
('resound' can be a synonym of 'ring')
'extremely remarkable safe' is the wordplay.
'extremely' suggests removing the centre.
'safe' becomes 'sound' ('sound' can be similar in meaning to 'safe').
'remarkable' with its centre taken out is 're'.
're'+'sound'='RESOUND'
'in' acts as a link.
(Other definitions for resound that I've seen before include "ring" , "Reverberate" , "Echo" .)