Right intake needs to be fixed for fibrous protein (7)
I believe the answer is:
keratin
'for fibrous protein' is the definition.
(I've seen this in another clue)
'right intake needs to be fixed' is the wordplay.
I cannot quite understand how this works, but
'right' could be 'r' (common abbreviation) and 'r' is found within the answer.
an anagram of 'intake' is 'keatin' which is located in the left over letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for keratin that I've seen before include "Hair, nails substance" , "Material in hooves and nails" , "Rate ink (anag) - fibrous protein" , "Protein found in hair and nails" , "Constituent of hair/nails" .)