She wants, say, about fifty quid (5)
I believe the answer is:
sally
'she' is the definition.
'say about fifty quid' is the wordplay.
'say' becomes 'as' (I've seen this in other clues).
'about' says the letters should be written backwards.
'fifty quid' becomes 'lly' (I can't explain this - if you can you should give a lot more credence to this answer).
'as' written backwards gives 'sa'.
'sa'+'lly'='SALLY'
'wants' acts as a link.
Can you help me to learn more?
(Other definitions for sally that I've seen before include "army" , "Witty riposte" , "- - Lunn, flat cake" , "excursion" , "trip" .)