Seizing compass, sailor put down drink (6,6)
I believe the answer is:
orange squash
'drink' is the definition.
(I've seen this before)
'seizing compass sailor put down' is the wordplay.
'seizing' indicates putting letters inside.
'compass' becomes 'range' (synonyms).
'sailor' becomes 'os' (ordinary seaman).
'put down' becomes 'quash' (both can mean to suppress or stop).
'range' inserted inside 'os' is 'oranges'.
'oranges'+'quash'='ORANGE SQUASH'
(Other definitions for orange squash that I've seen before include "Fruity soft drink" , "Soft fruit drink" , "concentrate!" .)