This is a fairly easy achievement to obtain.
While you are doing the quest in Trashlantis to guide the Clapstructor to the steel beam, it will eventually end with the Clapstructor becoming one with the steel beam. BEFORE leaving to return to the Mayor, talk to the Clapstructor. All the achievement requires is to talk to the Clapstructor once.
If you forget and wander off, you can always return to this area later.