A hundred and ten gathered round capital's highest point (6)
I believe the answer is:
climax
'highest point' is the definition.
(thesaurus)
'a hundred and ten gathered round capital's' is the wordplay.
'a hundred' becomes 'c' (roman numeral).
'and' means one lot of letters go next to another.
'ten' becomes 'x' (roman numeral).
'gathered round' is an insertion indicator.
'capital' becomes 'lima' (Lima is an example**).
'c'+'x'='cx'
'cx' enclosing 'lima' is 'CLIMAX'.
(Other definitions for climax that I've seen before include "Peak of emotion" , "(Reach the) highest level" , "exciting finale" , "Most exciting point" , "The decisive moment, in a novel or play say" .)