Designer Calvin (5)
I believe the answer is:
klein
'designer calvin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for klein that I've seen before include "French artist" , "who is warning about climate change?" , "Calvin ..., fashion designer" , "German mathematician who had a one-surfaced vessel named after him" , "no capacity for the bottle?" .)