I want to seek work in a store... Wrong, according to Duo! It should have been, "I want to find work in a store." Doesn't buscar mean? To look for, seek out, search for, etc. So wouldn't (find) be encontrar?
I want to look for work in a store is correct.
quiero - I want
buscar, in it's infinitive form because it's following a conjugated verb - to look for
trabajo, being used as a noun - work
en una tienda - in a store.
but earlier duo used "trabajo" as "job" and in English we would say a job.
I am OK with how the sentence was written, but find the idea of looking for work 'in a store' to be very confusing. Looking for a generic job in a 'specific' store, or a specific kind of store (e.g. clothing) is not strange and neither is looking for a specific 'kind of job' in stores generically (e.g. retail sales, mgmt, warehousing, purchasing, etc.), but looking for a 'generic job' in a 'generic store' is so unspecific that it makes no sense. How can you WANT something/anything so ... unspecific. This sentence is truly pointless.