Geronimo, say, quickly capturing hearts (6)
I believe the answer is:
apache
'geronimo' is the definition.
Both the definition and answer are singular nouns.
Perhaps they are linked in a way I don't understand?
'quickly capturing hearts' is the wordplay.
'quickly' becomes 'apace' (synonyms).
'capturing' indicates putting letters inside.
'hearts' becomes 'h' (abbreviation used in card games e.g. bridge).
'apace' placed around 'h' is 'APACHE'.
'say' acts as a link.
Can you help me to learn more?
(Other definitions for apache that I've seen before include "A peach of an Indian tribe?" , "Fierce Indian of American SW, or Paris ruffian" , "Tribal type" , "Geronimo was one" , "Geronimo's people" .)