Clever while seeming outwardly silly (3)
I believe the answer is:
sly
'clever' is the definition.
(sly means clever or cunning)
'while seeming outwardly silly' is the wordplay.
'while seeming' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'outwardly' means to remove the middle letters (only the outermost letters are used).
'silly' becomes 'loopy' (I've seen this before).
'loopy' with its middle taken out is 'ly'.
's'+'ly'='SLY'
Can you help me to learn more?
(Other definitions for sly that I've seen before include "Cunning, deceitful" , "Cunning; surreptitious" , "Cunning, foxy" , "Doing things in unpleasant and secret way" , "Crafty, devious" .)