Singular taxi-driver making a crust (6)

I believe the answer is:

scabby

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'making a crust' is the definition.
I can't tell whether this definition defines the answer.

'singular taxi-driver' is the wordplay.
'singular' becomes 's' (abbreviation in grammar).
'taxi-driver' becomes 'cabby' (I've seen this before).
's'+'cabby'='SCABBY'

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(Other definitions for scabby that I've seen before include "Blotchy" , "Despicable -- BBC, say (anag)" , "Despicable - with dried crusts" , "Covered with crusts of dried blood" , "Mangy" .)

I've seen this clue in The Times.

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