Fewer clothes, for example (6)

I believe the answer is:

lesson

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'example' is the definition.
(I know that example can be written as lesson)

'fewer clothes' is the wordplay.
'fewer' becomes 'less' (associated in meaning).
'clothes' becomes 'on' (I am not sure about this - if you are sure you should believe this answer much more).
'less'+'on'='LESSON'

'for' is the link.

Can you help me to learn more?

(Other definitions for lesson that I've seen before include "Moral" , "Single period of instruction" , "Sermon or teaching session" , "School period" , "Severe reproof" .)

I've seen this clue in The Sunday Times and The Times.

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