Peak in clear — one near borders (8)
I believe the answer is:
meridian
'peak' is the definition.
(thesaurus)
'in clear one near borders' is the wordplay.
'in clear' becomes 'rid' ('rid' can be a synonym of 'clear'. I am not sure about the 'in' bit.**).
'one' becomes 'i' (Roman numeral).
'near' becomes 'mean' (I've seen this before).
'borders' indicates putting letters inside.
'rid'+'i'='ridi'
'ridi' placed into 'mean' is 'MERIDIAN'.
Can you help me to learn more?
(Other definitions for meridian that I've seen before include "Imaginary great circle through North and South poles" , "Peak" , "Circle of longitude" , "Admire in great semi-circle on globe" , "Imaginary great circle on the earth passing through both poles" .)