A £50 total (3)

I believe the answer is:

all

I'm a little stuck... Click here to teach me more about this clue!

'total' is the definition.
(I've seen this before)

'a ps50' is the wordplay.
'ps50' becomes 'll' (I can't explain this - if you can you should believe this answer much more).
'a'+'ll'='ALL'

Can you help me to learn more?

(Other definitions for all that I've seen before include "Everybody; everything" , "None excluded" , "See 10 Across" , "Total" , "Entire" .)

I've seen this clue in the Evening Standard.

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