Says fish could be heading towards America (9)
I believe the answer is:
stateside
'be heading towards america' is the definition.
(in the United States of America)
'says fish' is the wordplay.
'says' becomes 'states' ('state' can be a synonym of 'say').
'fish' becomes 'ide' (type of fish).
'states'+'ide'='STATESIDE'
'could' acts as a link.
(Other definitions for stateside that I've seen before include "In the US" , "in America" .)