Crossword Genius

Not obviously silly, perhaps (5)

Ross

I believe the answer is:

slily

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

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

'silly perhaps' is the wordplay.
'perhaps' indicates an anagram.
'silly' anagrammed gives 'SLILY'.

Can you help me to learn more?

(Another definition for slily that I've seen is " in a crafty manner".)

I've seen this clue in the Evening Standard.
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