Compound supplied by Joanna Lumley (4)
I believe the answer is:
alum
'compound' is the definition.
(chemical compound)
'joanna lumley' is the wordplay.
'ALUM' is hidden in amongst the letters.
However, I'm uncertain how the hidden word is indicated.
'supplied by' is the link.
Can you help me to learn more?
(Other definitions for alum that I've seen before include "double sulphate" , "Potassium compound; IoW sandy bay" , "Sulphate used in dyeing and tanning" , "Compound used in dyeing and to stop bleeding" , "White mineral salt used in medicine and in dyeing" .)