Experts securing very good high points (6)
I believe the answer is:
apices
'high points' is the definition.
(I've seen this in another clue)
'experts securing very good' is the wordplay.
'experts' becomes 'aces' (ace is a kind of expert).
'securing' indicates putting letters inside.
'very good' becomes 'pi' (old-fashioned slang for pious).
'aces' going around 'pi' is 'APICES'.
(Other definitions for apices that I've seen before include "Mountain tops" , "tips" .)