Attempt nursing former queen where skin is treated (7)
I believe the answer is:
tannery
'where skin is treated' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'attempt nursing former queen' is the wordplay.
'attempt' becomes 'try' (synonyms).
'nursing' indicates putting letters inside.
'former queen' becomes 'anne' (Queen Anne, 18th-century queen. I am not sure about the 'former' bit.).
'try' enclosing 'anne' is 'TANNERY'.
Can you help me to learn more?
(Other definitions for tannery that I've seen before include "Leather factory" , "Leather-processing plant" , "Rather like sun lamp, arguably" , "where hides are treated" , "Where hides are made into leather" .)