Be honest about your intentions upfront. This lawyer may not be in a position to hire you but may know someone who is currently looking to hire.
More importantly, are you actually interested in this area of law? Is it contracts, labour and employment, IP? What about it is interesting? What else would you like to know other than if there is a job available?
Why don't you first ask to meet this lawyer for coffee? It is off-putting to have someone only contact you because they want a job, as opposed to building a real mentor-mentee relationship, friendship, network, etc.