Dollar alien found in container (6)
I believe the answer is:
bucket
'container' is the definition.
(bucket is a kind of container)
'dollar alien' is the wordplay.
'dollar' becomes 'buck' ('buck' can be a synonym of 'dollar').
'alien' becomes 'et' (extra terrestrial).
'buck'+'et'='BUCKET'
'found in' is the link.
(Other definitions for bucket that I've seen before include "Round open water container with handle" , "Carrier for liquids" , "Waterwheel compartment" , "Round container for carrying" , "Resembling soil" .)