River rising to claim female, small and delicate (5)
I believe the answer is:
elfin
'small and delicate' is the definition.
(elfin means small or cute)
'river rising to claim female' is the wordplay.
'river' becomes 'nile' (Nile River is an example).
'rising' says the letters should be written in reverse (going up in a down clue).
'to claim' indicates putting letters inside (inserted letters are claimed or taken in).
'female' becomes 'f' (common abbreviation).
'nile' backwards is 'elin'.
'elin' going around 'f' is 'ELFIN'.
(Other definitions for elfin that I've seen before include "Spritely" , "Pixie-like" , "Small and delicate like fairy" , "Petite and charming" , "Describing Santa's helpers" .)