Dutch explorer positioned to return with Queen, say (6)
I believe the answer is:
tasman
'dutch explorer' is the definition.
(17th-century explorer Abel Tasman)
'positioned to return with queen say' is the wordplay.
'positioned' becomes 'sat' (sitting is a kind of positioning).
'to return' says the letters should be written backwards.
'with' says to put letters next to each other.
'queen say' becomes 'man' (queen is a kind of man).
'sat' reversed gives 'tas'.
'tas'+'man'='TASMAN'
(Other definitions for tasman that I've seen before include "Australian strait" , "Abel --, Dutch navigator" , "explored Pacific" , "Dutch antipodean explorer" , "Sea named after Dutch navigator" .)