Pet butterfly, perhaps (6)
I believe the answer is:
stroke
This clue is a double definition.
'pet' is the first definition.
(I've seen this before)
'butterfly perhaps' is the second definition.
(butterfly stroke is a swimming stroke)
(Other definitions for stroke that I've seen before include "Brush gently - coup" , "Manner of swimming - caress with hand" , "Caress gently" , "Fit of apoplexy" , "Caress - rower" .)