Northern dialect some Scots use (6)
I believe the answer is:
scouse
'northern dialect some scots use' is the definition.
I can't tell whether this definition defines the answer.
'northern dialect some scots use' is the wordplay.
'northern' shows that the letters should be reversed in order (in a down clue, letters go up or 'north').
'dialect' becomes 'oc' (I can't justify this - if you can you should believe this answer much more).
'some' indicates taking the first letters.
The first letter of 'scots' is 's'.
'oc'+'s'='ocs'
'ocs' back-to-front is 'sco'.
'sco'+'use'='SCOUSE'
Can you help me to learn more?
(Other definitions for scouse that I've seen before include "Liverpudlian accent" , "What they speak in Liverpool?" , "Liverpool accent" , "Slang for native of Liverpool" , "another city's dialect" .)