Possibly penetrating hiss softly coming to one's ears (6)
I believe the answer is:
spears
'possibly penetrating hiss softly coming to one's ears' is the definition.
I can't judge whether this definition defines the answer.
'softly coming to one's ears' is the wordplay.
'softly' becomes 'p' (short for piano, musical term for softly).
'coming to' means one lot of letters go next to another.
'one's' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'p' after 's' is 'sp'.
'sp'+'ears'='SPEARS'
Can you help me to learn more?
(Other definitions for spears that I've seen before include "Long pointed weapons" , "pop singer" , "Javelins" , "Some broccoli" , "Bits of green veg" .)