Shape of some galaxies (6)
I believe the answer is:
spiral
'shape of some galaxies' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for spiral that I've seen before include "In flight manoeuvre" , "design for some staircase" , "New Zealand native" , "Shape of a coiled spring" , "Sir, pal inds in continuous loops" .)