Scene of battle keeps retaining sharpness (8)
I believe the answer is:
hastings
'scene of battle' is the definition.
'hastings' can be an answer for 'battle' (Battle of Hastings, 1066 battle). I am not certain of the 'scene of' bit.
'keeps retaining sharpness' is the wordplay.
'keeps' becomes 'has' (keep can mean to have or possess).
'retaining sharpness' becomes 'tings' (I am not sure about this - if you are sure you should believe this answer much more).
'has'+'tings'='HASTINGS'
Can you help me to learn more?
(Other definitions for hastings that I've seen before include "Ten sixty six battle" , "South coast resort" , "Sussex battle" , "Ten Sixty-Six battle" , "Harold's objective?" .)