The first to permit candle material (6)
I believe the answer is:
tallow
'candle material' is the definition.
(I've seen this in another clue)
'the first to permit' is the wordplay.
'the first to' becomes 't' (1st letter of 'to').
'permit' becomes 'allow' (synonyms).
't'+'allow'='TALLOW'
(Other definitions for tallow that I've seen before include "Animal fat used to make ..." , "Fat processed for making candles" , "burning fat" , "Contributor to soap" , "Animal fat used in candles, soap etc" .)