Beetles are the vehicle to break into bass playing (7)
I believe the answer is:
scarabs
'beetles' is the definition.
(scarab is a kind of beetle)
'the vehicle to break into bass playing' is the wordplay.
'the vehicle' becomes 'car' (car is a kind of vehicle).
'to break into' indicates putting letters inside.
'playing' indicates an anagram.
'bass' with letters rearranged gives 'sabs'.
'car' put into 'sabs' is 'SCARABS'.
'are' acts as a link.
(Other definitions for scarabs that I've seen before include "Beetles considered divine by ancient Egyptians" , "Large dung beetles" .)