£50 charges to procure exclusive dress for occasion (4,4)
I believe the answer is:
ball gown
'dress for occasion' is the definition.
(dress for attending a ball)
'ps50 charges to procure exclusive' is the wordplay.
'ps50' becomes 'll' (I can't justify this - if you can you should believe this answer much more).
'charges' indicates putting letters inside (charge can mean to charge into something).
'to procure' becomes 'bag' (bag can mean to secure or procure).
'exclusive' becomes 'own' (one's own, excluding others).
'll' inserted within 'bag' is 'ballg'.
'ballg'+'own'='BALL-GOWN'
(Other definitions for ball gown that I've seen before include "formal dress" , "costume" .)