Spiral-shaped (7)
I believe the answer is:
helical
'spiral-shaped' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for helical that I've seen before include "Like a spiral or spring" , "Curled like corkscrew" , "Spiral-shaped" , "Like the pattern on a snail's shell" , "In the form of a spiral" .)