Old man restraining people heading off for a dance (5)
I believe the answer is:
polka
'for a dance' is the definition.
(polka is a kind of dance)
'old man restraining people heading off' is the wordplay.
'old man' becomes 'pa' (both can mean father).
'restraining' indicates putting letters inside.
'people' becomes 'folk' (informal term for people).
'heading off' means to remove the first letter.
'folk' with its first letter removed is 'olk'.
'pa' enclosing 'olk' is 'POLKA'.
(Other definitions for polka that I've seen before include "Lively dance, originally from Bohemia" , "Take rapid steps" , "Dance in fast time with three steps and a hop" , "Folk dance" , "An originally Bohemian dance" .)