Ply for hire/trade/business
Definition 1 of 1
Pro Tip 1/3Occupational Use
Used for professions where there's direct selling of services or skills, especially in transport or freelance work. 
Street performers ply their trade in the town square to entertain people and earn money.
Pro Tip 2/3Active Pursuit
'Ply for hire/trade/business' implies actively seeking work or customers, not passively waiting for them. 
After setting up her food stall, she plied for business at the local market.
Pro Tip 3/3Economic Activity
Often used in discussions about the economy to discuss different sectors and how they operate. 
During the festival, many locals ply their trades to cater to the increase in tourists.