Is spread betting clean? Yes, every so often! (6)

I believe the answer is:

splays

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

'is spread' is the definition.
I can't tell whether this defines the answer.

'betting clean? yes every so often' is the wordplay.
'betting' becomes 'sp'.
'every so often' means one should take alternating letters.
'clean'+'yes'='cleanyes'
The alternate letters of 'cleanyes' are 'lays'.
'sp'+'lays'='SPLAYS'

Can you help me to learn more?

(Other definitions for splays that I've seen before include "Spreads apart, or bends outwards" , "Spreads open" , "fans out" .)

I've seen this clue in The Times.

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