Frothy letter that's turned up for me (5)

I believe the answer is:

spume

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'frothy letter that's turned up for me' is the definition.
I can't tell whether this definition defines the answer.

'letter that's turned up for me' is the wordplay.
'letter' becomes 's' ().
'that's turned' is a reversal indicator.
'for' means one lot of letters go next to another.
'up' written backwards gives 'pu'.
's'+'pu'+'me'='SPUME'

Can you help me to learn more?

(Other definitions for spume that I've seen before include "Froth on waves" , "Sea foam, froth" , "Foam on waves" , "Surf" .)

I've seen this clue in the Evening Standard.

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