Crossword Genius

When caught out, witch did a sketch and backed off (8)

Ross

I believe the answer is:

withdrew

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

'when caught out witch did a sketch' is the definition.
I can't tell whether this defines the answer.

'and backed off' is the wordplay.
'and' becomes 'with'.
'backed off' becomes 'drew' (I can't justify this - if you can you should believe this answer much more).
'with'+'drew'='WITHDREW'

Can you help me to learn more?

(Other definitions for withdrew that I've seen before include "Backed away or bowed out" , "Took away; retreated" , "retired" , "Took back" , "Scratched" .)

I've seen this clue in the Sydney Morning Herald.
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