Dumbbell exercise (4)
I believe the answer is:
curl
'dumbbell exercise' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for curl that I've seen before include "Coiled lock of hair" , "Twist (e.g. of hair)" , "Spiral or coil" , "Play on ice" , "Hair piece; flick up" .)