These could be silly so-and-sos without intelligence (7)
I believe the answer is:
nitwits
'these could be silly' is the definition.
The definition suggests an adverb but the answer is not.
'and-sos without intelligence' is the wordplay.
'and-sos' becomes 'nits' (I can't justify this - if you can you should give a lot more credence to this answer).
'without' is an insertion indicator ('without' can be similar in meaning to 'outside').
'intelligence' becomes 'wit' (wit is a kind of intelligence).
'nits' going around 'wit' is 'NITWITS'.
'so' acts as a link.
Can you help me to learn more?
(Other definitions for nitwits that I've seen before include "Silly or foolish people" , "suckers" .)