Writer heads north over a large country (5)
I believe the answer is:
nepal
'country' is the definition.
(I know that Nepal is Asian country)
'writer heads north over a large' is the wordplay.
'writer' becomes 'pen' (something which writes).
'heads north' is a reversal indicator (in a down clue, letters go up or 'north').
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'large' becomes 'L' (eg in clothes sizes).
'pen' written backwards gives 'nep'.
'nep'+'a'+'l'='NEPAL'
(Other definitions for nepal that I've seen before include "neighbour of Tibet" , "Small lake" , "Hindu kingdom in south Asia" , "land" , "Asian country -- plane (anag)" .)