drip feed

Concise Oxford English Dictionary © 2008 Oxford University Press:
drip feed

▶noun a device for introducing fluid drop by drop into a system. ▶verb (drip-feed)

• 1 introduce (fluid) drop by drop.

  ■ supply (a patient) with fluid through a drip.

• 2 provide gradually and in small amounts: their correspondence is being drip-fed to newspapers.