It could be a sea anemone, parrot said softly (5)
I believe the answer is:
polyp
'it could be a sea anemone parrot' is the definition.
The definition suggests a singular noun which matches the answer.
'said softly' is the wordplay.
'said' becomes 'poly' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'softly' becomes 'p'.
'poly'+'p'='POLYP'
Can you help me to learn more?
(Other definitions for polyp that I've seen before include "Small growth, usually benign" , "Small growth on a mucous membrane" , "Sea anemone, for example" , "Small growth (medical)" , "Sea creature; small growth" .)