Met and designed bike (6)
I believe the answer is:
tandem
'bike' is the definition.
(I know that tandem is a type of bike)
'met and designed' is the wordplay.
'designed' indicates an anagram (designed with the letters).
'met'+'and'='metand'
'metand' anagrammed gives 'TANDEM'.
(Other definitions for tandem that I've seen before include "Bike for two cyclists" , "Bike with two saddles" , "Two-seat bicycle" , "Two-person cycle" , "Bicycle made for two" .)