Fine South coast resort neither opens nor closes (6)
I believe the answer is:
righto
'fine' is the definition.
(both can mean 'yes' or 'alright')
'south coast resort neither opens nor closes' is the wordplay.
'south coast resort' becomes 'brighton' (I've seen this before).
'neither opens nor closes' means to look at the middle letters (the opening and closing letters are removed).
The centre of 'brighton' is 'RIGHTO'.
(Other definitions for righto that I've seen before include "Agreed" , "Okey-dokey" , "OK" , "I agree (informal)" , "Okay!" .)