To get a bus round central places is something you can count on (6)
I believe the answer is:
abacus
'something you can count on' is the definition.
(I've seen this in another clue)
'to get a bus round central places' is the wordplay.
'to get' means one lot of letters go next to another.
'round' means one lot of letters goes inside another.
'central' means to look at the middle letters.
The middle letters of 'places' are 'ac'.
'bus' placed around 'ac' is 'bacus'.
'a'+'bacus' is 'ABACUS'.
'is' is the link.
(Other definitions for abacus that I've seen before include "Old counter" , "Early counting-frame" , "Calculating frame" , "As a cub (anag)" , "Basic calculator makes" .)