Lizard in S American region, one moving to prime position (6)
I believe the answer is:
iguana
'lizard' is the definition.
(iguana is a kind of lizard)
's american region one moving to prime position' is the wordplay.
I cannot quite see how this works, but
'american' could be 'a' (common abbreviation - e.g. in organisation names) and 'a' is found within the answer.
'one' could be 'un' (northern English dialect form of 'one') and 'un' is found within the leftover letters.
This explanation may well be incorrect...
'in' is the link.
(Other definitions for iguana that I've seen before include "Large tree-climbing lizard of tropical America" , "Tropical American lizard" , "Animal" , "Tropical spiny lizard" , "Something like a monitor" .)