Periodically admits actor into dance (5)
I believe the answer is:
disco
'dance' is the definition.
(disco can mean a dance event)
'periodically admits actor' is the wordplay.
'periodically' means one should take alternating letters (letters must be selected 'every so often').
'admits'+'actor'='admitsactor'
The alternating letters of 'admitsactor' are 'DISCO'.
'into' is the link.
(Other definitions for disco that I've seen before include "Dancing venue" , "party for dancers" , "Nightclub with recorded music, in short" , "Youngsters' dance venue" , "One might get down to this" .)