Reversed mystic symbol inscribed with a second charm (7)
I believe the answer is:
enamour
'charm' is the definition.
(I know that charm can be written as enamour)
'reversed mystic symbol inscribed with a second' is the wordplay.
'reversed' shows that the letters should be reversed in order.
'mystic symbol' becomes 'rune' (I've seen this in another clue).
'inscribed with' means one lot of letters goes inside another (I've seen this in other clues).
'second' becomes 'mo' (both are short periods of time).
'rune' in reverse letter order is 'enur'.
'a'+'mo'='amo'
'enur' enclosing 'amo' is 'ENAMOUR'.
(Other definitions for enamour that I've seen before include "Charm, captivate" , "Inspire with love; charm" , "Delight" , "entrance" , "Our name (anag)" .)