Tin-pot is an insult, and a rather old-fashioned, British-sounding one. You put it in front of a noun to say that a person or an organisation is small, cheap and badly run — but is puffing itself up as if it were grand. The gap between how important they think they are and how important they actually are is the whole point of the word. The classic use is 'a tin-pot dictator': someone who rules a small place, wears a chest full of medals he gave himself, and behaves like a world power. You can also say a tin-pot company, a tin-pot little army, a tin-pot outfit. Note the tone: it is not a neutral word for 'small'. A small shop run honestly is not tin-pot. It becomes tin-pot when there are grand titles, big claims and nothing behind them. It sounds like a newspaper column or an angry uncle rather than everyday speech, and younger speakers use it much less than older ones. Some writers spell it tinpot or tin pot; all three appear.