Appearing now and then in role before interval (4-4)
I believe the answer is:
part-time
'appearing now and then' is the definition.
(eg appearing in a job sometimes)
'role before interval' is the wordplay.
'role' becomes 'part' (eg a part or role in a film).
'before' is a charade indicator (letters next to each other).
'interval' becomes 'time' (synonyms).
'part'+'time'='PART-TIME'
'in' is the link.
(Other definitions for part-time that I've seen before include "Working reduced hours" , "(Working) for a few hours a week" , "For less than the standard number of hours" , "Not working full hours" , "This job does not require all of the working week" .)