Whirlpool: two daughters dropping in extremely eagerly (4)
I believe the answer is:
eddy
'whirlpool two' is the definition.
'eddy' can be an answer for 'whirlpool' (synonyms). I am not sure about the 'two' bit.
'daughters dropping in extremely eagerly' is the wordplay.
'daughters' becomes 'd'.
'dropping' becomes 'd' (this might be a standard abbreviation I've not previously seen).
'in' means one lot of letters goes inside another.
'extremely' means to remove the middle letters.
'eagerly' with its centre removed is 'ey'.
'd'+'d'='dd'
'dd' put into 'ey' is 'EDDY'.
Can you help me to learn more?
(Other definitions for eddy that I've seen before include "A small whirl of water" , "Little whirlpool" , "Man" , "dangerous bit of water" , "Founder of sect" .)