Outstanding male feature's very soft in water (5,5)
I believe the answer is:
adams apple
'outstanding male feature's' is the definition.
(prominent feature of the throat)
'very soft in water' is the wordplay.
'very soft' becomes 'pp' (musical abbreviation for pianissimo).
'in' means one lot of letters goes inside another.
'water' becomes 'adams ale' (humorous term for water).
'pp' placed within 'adamsale' is 'ADAMS APPLE'.
(Other definitions for adams apple that I've seen before include "Thyroid cartilage projection in throat" , "Charactistic of a man" , "External protuberance of part of larynx" , "Prominence on the throat" , "one shows swallowing motion" .)