Perfect lady about fifty (8)
I believe the answer is:
peerless
'perfect' is the definition.
(thesaurus)
'lady about fifty' is the wordplay.
I cannot quite see how this works, but
'fifty' could be 'l' (Roman numeral) and 'l' is found within the answer.
'lady' could be 'peeress' (female peer) and 'peeress' is found within the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for peerless that I've seen before include "Excellent" , "superb" , "Unique" , "Unequalled" , "Unmatched" .)