Pet to beat? (6)
I believe the answer is:
stroke
I believe this clue is a double definition.
'pet' is the first definition.
(thesaurus)
'beat?' is the second definition.
(beat is a kind of stroke)
'to' acts as a link.
(Other definitions for stroke that I've seen before include "Rub gently" , "butterfly?" , "One of eight" , "Brush gently - coup" , "one of rowing crew" .)