About to damage talisman (5)
I believe the answer is:
charm
'talisman' is the definition.
('charm' can be a synonym of 'talisman')
'about to damage' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'to damage' becomes 'harm' ('harm' can be a synonym of 'damage'**).
'c'+'harm'='CHARM'
(Other definitions for charm that I've seen before include "For example, olde-worlde character" , "Appeal; trinket" , "Enrapture" , "Lure" , "Entice" .)