In the teens, going out is great (7)
I believe the answer is:
intense
'great' is the definition.
(thesaurus)
'in the teens going out' is the wordplay.
'going out' indicates an anagram (out can mean wrong or inaccurate).
'teens' with letters rearranged gives 'tense'.
'in'+'tense'='INTENSE'
'is' is the link.
(Other definitions for intense that I've seen before include "Fierce - deep" , "Extremely earnest or serious" , "'Acute, extreme (7)'" , "In an extreme degree" , "say, description of campers?" .)