I believe the occupation reads Lunchroom. Finding the Industry Code definition for "619V" would further clarify the occupation, food services? if Lunchroom, or cleaning services? if Laundryroom.
The Boston Public Library (bpl dot org, then "Ask a Librarian") might have a 1930 residential Directory (plus minus a few years) with Andrew and Catherine on/near Cameron Street. Directories sometimes list specific places of employment.
You'll find his naturalization index card, petition, and oath (1922) on fold3 dot com (+andrew +christie +naturalization then narrow the field choices) on which he listed as Waiter, resides 33 Falmouth St, and his wife Eunice is listed as deceased. Fold3 also has searchable Directories for Boston up to 1926 (he is not obvious on the 1925 nor 1926 City i.e. categorized by business Directory.)
1918 Directory Boston CHRISTIE Andrew, clerk, 33 Falmouth CHRISTIE Andrew, optician, 367 Boylston, resides Quincy MA
One lengthy step further once you have his naturalization papers is his Alien Registration (c 1940s) IF he did so thru (formerly INS or Immigration and Naturalization Services) now Dept of Homeland Security online. This might list employer.
His 1918 WWI Draft Registration (Ancestry) states he was employed as Waiter at A.F. Landers Co. at 20 Huntington Ave, Boston (just outside the Boston Public Library!). Landers is very fuzzy, and he and his then wife Eunice A Wright (mn Beckstein, b abt 1871, Albany NY) resided at 33 Falmouth St, Boston. (Family Search dot org).
hmm, the 1918 Boston City (Business) Directory, search for LANDERS hits include "Prosperity Laundry (A."E." Landers), 184 Brookside Ave, JP" or Jamaica Plain, a neighborhood in Boston.
His WWII Draft Registration (c1942) gives his employer as City of Boston, City Hospital, at 818 Harrison Ave, Boston. He and his wife Catherine reside at 58 Hartford St, Dorchester, another neighborhood in Boston. (Ancestry)
He should have applied for a Social Security Number; the original application may list his employer. I think I googled instructions and criteria on how to request that and found a "form" Freedom of Information Act (FOIA) letter to get it.