Met and changed a bike (6)
I believe the answer is:
tandem
'a bike' is the definition.
(I know that tandem is a type of bike)
'met and changed' is the wordplay.
'changed' is an anagram indicator.
'met'+'and'='metand'
'metand' is an anagram of 'TANDEM'.
(Other definitions for tandem that I've seen before include "two people working together" , "Two-person cycle" , "Two-seat bicycle" , "Bicycle for girl in 32 Across" , "Bicycle for two (plus)" .)