Among those characters in speed dating falling head over heels with Count (3)
I believe the answer is:
add
'count' is the definition.
(adding is a kind of counting)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for add that I've seen before include "do some mathematics" , "put two and two together" , "Increase" , "Go further" , "Include" .)