lead in

Short definition from Wiktionary

Verb

1. 1
   Used other than figuratively or idiomatically: see lead, in.
2. 2
   To introduce, to mark the beginning of something, especially in music.

Noun

1. 1
   Misspelling of lead-in.
2. 2
   An introduction; something that leads into the beginning of something.
3. 3
   A region of data at the beginning of a compact disc, holding the table of contents.
4. 4
   A short phrase that begins the caption of a photograph.