Get the boat to float in (6)
I believe the answer is:
obtain
'get' is the definition.
(I know that get can be written as obtain)
'boat to float in' is the wordplay.
'to float' is an anagram indicator (I've seen 'floating' mean this (float can mean fluctuate or oscillate)).
'boat' with letters rearranged gives 'obta'.
'obta'+'in'='OBTAIN'
'the' is the link.
(Other definitions for obtain that I've seen before include "Get one's hands on" , "Get - secure" , "Gain possession of" , "Take possession of" , "Get or lay hold of" .)