Festival lights surrounding mother (9)
I believe the answer is:
candlemas
'festival' is the definition.
(I have seen 'A festival' mean 'candlemas' so perhaps 'festival' could also mean 'candlemas')
'lights surrounding mother' is the wordplay.
'lights' becomes 'candles' (candle is a kind of light).
'surrounding' means one lot of letters goes inside another.
'mother' becomes 'ma' (ma can mean mother).
'candles' placed around 'ma' is 'CANDLEMAS'.
(Other definitions for candlemas that I've seen before include "February Christian festival" , "feast day" , "Feast of the Purification of the Virgin Mary" , "church festival" .)