Female scout cast Gielgud in role originally (4,5)
I believe the answer is:
girl guide
'female scout' is the definition.
The definition suggests a singular noun which matches the answer.
'cast gielgud in role originally' is the wordplay.
'cast' is an anagram indicator (letters are dispersed or cast around).
'originally' says to take the initial letters.
The initial letters of 'in role' is 'ir'.
'gielgud'+'ir'='gielgudir'
'gielgudir' anagrammed gives 'GIRL GUIDE'.
Can you help me to learn more?
(Other definitions for girl guide that I've seen before include "Troop member" , "member of worldwide movement" , "Female equivalent of Boy Scout" .)