Father confused America producing freshwater protozoans (9)
I believe the answer is:
paramecia
'producing freshwater protozoans' is the definition.
I can't judge whether this definition defines the answer.
'father confused america' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'confused' indicates anagramming the letters.
'america' with letters rearranged gives 'ramecia'.
'pa'+'ramecia'='PARAMECIA'
Can you help me to learn more?
(Another definition for paramecia that I've seen is " Minuscule creatures".)