Big wave in possible contact with a coaster (6)

I believe the answer is:

roller

I'm a little stuck... Click here to teach me more about this clue!

'big wave' is the definition.

I can't explain the remainder of the clue.

(Other definitions for roller that I've seen before include "Heavy sea wave and hair curler" , "Wave - wave-maker" , "One may be employed to paint" , "Kind of skate" , "Wave; castor; cylinder" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app