Ran overseas and brought back an echo sounder (5)
I believe the answer is:
sonar
'echo sounder' is the definition.
(synonyms)
'ran overseas and brought back an' is the wordplay.
I cannot really see how this works, but
an anagram of 'ran' is 'nar' which is present in the answer.
The remaining letters 'so' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sonar that I've seen before include "Underwater location equipment" , "Echo-sounding equipment" , "Detection system at sea" , "Sub's navigation" , "Underwater echo sounder" .)