Islander takes precaution moving across river (6,5)
I believe the answer is:
puerto rican
'islander' is the definition.
(I've seen this before)
'precaution moving across river' is the wordplay.
'moving' is an anagram indicator.
'across' indicates putting letters inside.
'river' becomes 'r'.
'precaution' with letters rearranged gives 'puertoican'.
'puertoican' enclosing 'r' is 'PUERTO RICAN'.
'takes' is the link.
(Other definitions for puerto rican that I've seen before include "Caribbean from San Juan, perhaps" , "Islander" .)