Out of control in the main (6)

I believe the answer is:

adrift

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'out' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

(Other definitions for adrift that I've seen before include "Floating uncontrolled" , "Not anchored, floating freely" , "Wandering aimlessly" , "Afloat without steerage" , "cut loose" .)

I've seen this clue in The Irish News.

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