Ridge where one hundred take breather (5)
I believe the answer is:
crest
'ridge' is the definition.
(thesaurus)
'one hundred take breather' is the wordplay.
'one hundred' becomes 'c' (Roman numeral).
'take' is a charade indicator (letters next to each other).
'breather' becomes 'rest' (I've seen this before).
'c'+'rest'='CREST'
'where' is the link.
(Other definitions for crest that I've seen before include "Heraldic device representing a family" , "Top of a ridge/wave" , "Highest point" , "Tuft" , "Top point of hill or wave" .)