Jellyfish in sea north of the states (6)
I believe the answer is:
medusa
'jellyfish' is the definition.
(synonyms)
'sea north of the states' is the wordplay.
'sea' becomes 'med' (abbreviation of Mediterranean).
'north of' means one lot of letters go next to another (in a down clue, some letters go above others).
'the states' becomes 'usa' (I've seen this before).
'med'+'usa'='MEDUSA'
'in' acts as a link.
(Other definitions for medusa that I've seen before include "Form of jellyfish" , "Mythical woman transformed into a Gorgon" , "Hideous female" , "all her visitors got stoned" , "Mythical woman with snakes for hair" .)