middleman

Short definition from Wiktionary

Noun

1. 1
   An intermediary, agent between two (or more) parties.
2. 2
   An intermediate dealer between the manufacturer and the retailer or customer.
3. 3
   One who rents land in large tracts, and lets it in small portions to the peasantry.

Verb

1. 1
   To act as a middleman or intermediary.