Somebody great, formerly, from south Cork (7)
I believe the answer is:
stopper
'cork' is the definition.
(a cork stops a bottle)
'somebody great formerly from south' is the wordplay.
I cannot really see how this works, but
'great' could be 'top' and 'top' is present in the answer.
'south' could be 's' (abbreviation) and 's' is located in the answer.
The remaining letters 'per' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stopper that I've seen before include "Cork - goalkeeper?" , "Perhaps cork" , "Plug for a bottle" , "Maybe cork" , "One who checks" .)