Hill climber's first to display necklace (4)
I believe the answer is:
torc
'necklace' is the definition.
(medieval neck ornament)
'hill climber's first' is the wordplay.
'hill' becomes 'tor' (tor is a kind of hill).
'climber's first' becomes 'c' (1st letter of 'climber').
'tor'+'c'='TORC'
'to display' acts as a link.
(Other definitions for torc that I've seen before include "Celtic metal neck-ring" , "Rigid circular necklace" , "Metal neck ornament of ancient Britons" , "Choker" , "Metal armband worn by Ancient Britons" .)