Terribly close, far outside (8)
I believe the answer is:
alfresco
'outside' is the definition.
(synonyms)
'terribly close far' is the wordplay.
'terribly' indicates an anagram.
'close'+'far'='closefar'
'closefar' is an anagram of 'ALFRESCO'.
(Other definitions for alfresco that I've seen before include "where it's cool" , "Outdoors, meal perhaps" , "In the open air" , "Outside" , "Open-air" .)