1000 kg of cotton needed (5)
I believe the answer is:
tonne
'1000 kg' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Maybe there's a link between them I don't understand?
'of cotton needed' is the wordplay.
'of' says the answer is hidden in the clue.
'TONNE' is hidden in the letters of 'cotton needed'.
Can you help me to learn more?
(Other definitions for tonne that I've seen before include "Metric weight unit" , "1000 kilograms" , "1,000 kg" , "A thousand kilogrammes" , "Heavyweight" .)