Not so far from Cork? (6)
I believe the answer is:
closer
'not so far' is the definition.
('close' can be the opposite of 'far' so perhaps 'closer' is reasonable for 'not so far')
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for closer that I've seen before include "within a shorter distance" , "Nearer or more intimate" , "More near or imminent" , "Comparatively near" , "Less distant" .)