Don't go out and do naughties around river (4,2)
I believe the answer is:
stay in
'don't go out' is the definition.
(to stay in is to stay at home)
'and do naughties around river' is the wordplay.
I cannot quite understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
'river' could be 'tay' (Scottish river) and 'tay' is found in the answer.
The remaining letters 'si' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stay in that I've seen before include "Not go out" , "One not going out" , "Remain at home" .)