Spiraled (7)
(Other definitions for helical that I've seen before include "Curled like corkscrew" , "Spiral-shaped" , "In the form of a spiral" , "Like the pattern on a snail's shell" , "Like a spiral or spring" .)
'spiraled' is the definition.
('corkscrew' can be a synonym of 'spiral')
This is all the clue.
(Another definition for corkscrewed that I've seen is " Bottle stoppers may have been this".)