One self-absorbed Russian's beginning to concede ground (9)
I believe the answer is:
narcissus
'one self-absorbed' is the definition.
I can't judge whether this definition defines the answer.
'russian's beginning to concede ground' is the wordplay.
'beginning to' suggests taking the first letters.
'ground' indicates an anagram ('grind' the letters into a new form).
The first letter of 'concede' is 'c'.
'russians'+'c'='russiansc'
'russiansc' with letters rearranged gives 'NARCISSUS'.
Can you help me to learn more?
(Other definitions for narcissus that I've seen before include "Self-centred youth" , "Legendary youth who fell in love with his own reflection" , "Mythical egotist" , "Flower of daffodil family" , "He saw himself as most adorable" .)