Hearts captured by artist with a flower (6)
I believe the answer is:
dahlia
'flower' is the definition.
(dahlia is a kind of flower)
'hearts captured by artist with a' is the wordplay.
'hearts' becomes 'h' (abbreviation used in card games e.g. bridge).
'captured by' means one lot of letters goes inside another.
'artist' becomes 'dali' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'h' placed into 'dali' is 'dahli'.
'dahli'+'a'='DAHLIA'
(Other definitions for dahlia that I've seen before include "Garden plant with large brightly-coloured flowers" , "conspicuous bloomer" , "Ali had (anag) - showy flower" , "Flower from tuber" , "Lia had this flower, strangely" .)