Continue talking annoyingly about old pointed weapon (7)
I believe the answer is:
harpoon
'pointed weapon' is the definition.
'harpoon' can be an answer for 'weapon' (I've seen this before). I'm not sure about the 'pointed' bit.
'continue talking annoyingly about old' is the wordplay.
'continue talking annoyingly' becomes 'harp on' (to harp on is to continue talking).
'about' indicates putting letters inside.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'harpon' placed around 'o' is 'HARPOON'.
Can you help me to learn more?
(Other definitions for harpoon that I've seen before include "killer at sea" , "Weapon for whales" , "Spear with a line attached for fishing" , "Barbed whale-spear" , "Barbed missile" .)