leg up

Short definition from Wiktionary

Noun

1. 1
   The act of assisting another's progress over a wall or other obstacle by forming a step for one of their feet with one's hands.
2. 2
   A boost, a sudden improvement; an advantage, an edge.
3. 3
   Assistance, help given to get started or overcome a problem or obstacle.
4. 4
   Alternative form of leg up.

Verb

1. 1
   To walk a horse on a hard surface regularly.