This question is pretty vague, as it depends on the specific country/sector.
Generally speaking, a sector ETF for that particular country/region is a good starting point. If none exist, stocks or corporate bonds could be an alternative.
Government bonds/FX products are less attractive as they're more closely tied to the overall GDP and are only a proxy for the specific sector you're interested in.
Other considerations are whether it's a developed or emerging country, the local currency, the main sectors/commodities that contribute to the economy, the correlation with other countries/asset classes, liquidity...
Last but not least, if you have strong reasons to believe that, other people might too, i.e. it might already be priced in and limit your profit potential.