Clue: Starter missing final touch, brunch with half missing: dig in! (8)
Answer: ENTRENCH
Explanation: Definition: dig in
A charade of ENTRÉ[e] ('starter'; as a dinner course, the word is something of a moveable feast: a starter, intermediate course, or a main course; musically, it is more firmly a prelude) minus the last letter ('missing final touch'); plus '[bru]NCH' minus the first three letters ('with half missing' – unusual to have the first half missing, but why not?).