What's no use, old, terribly lumpy (8)

I believe the answer is:

nodulose

I'm a little stuck... Click here to teach me more about this clue!

'lumpy' is the definition.
(I've seen this before)

'what's no use old terribly' is the wordplay.
'what's' becomes 'n' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'no' becomes 'o' (resembles 0 - 'no' can mean 'zero').
'terribly' indicates an anagram.
'use'+'old'='useold'
'useold' anagrammed gives 'dulose'.
'n'+'o'+'dulose'='NODULOSE'

Can you help me to learn more?

(Other definitions for nodulose that I've seen before include "with knobs on" , "Like a small swelling" , "Lumpy" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.