Something spicy about sweetheart (5)
I believe the answer is:
clove
'something spicy' is the definition.
'about sweetheart' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'sweetheart' becomes 'love' (I've seen this before**).
'c'+'love'='CLOVE'
(Other definitions for clove that I've seen before include "Spice, used whole or ground" , "Dried flower bud spice" , "Payment for hostage" , "Pungent spice" , "Flower bud used as a spice" .)