This is a charade - where separate words or phrases are joined together to form the answer. Look for parts of the clue that can be combined.
The clue contains a personal claim ('I'm...') followed by what an old-fashioned baggage-carrier might be called. These two parts combine directly to spell out the answer.
Answer: IMPORTER | This splits as I'M + PORTER. The personal claim 'I'm' combines with 'porter' (an old-fashioned baggage-carrier) to give IMPORTER (trader).