Beeb acts occasionally to create hit (4)
I believe the answer is:
beat
'hit' is the definition.
'beeb acts occasionally' is the wordplay.
'occasionally' means one should take alternating letters.
'beeb'+'acts'='beebacts'
The alternating letters of 'beebacts' are 'BEAT'.
'to create' acts as a link.
(Other definitions for beat that I've seen before include "Flog" , "Rhythmic music unit" , "Do better than another in competition" , "Throb; surpass" , "Overcome or hit repeatedly" .)