Thanks for every candle (5)
I believe the answer is:
taper
'candle' is the definition.
(synonyms)
'thanks for every' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'for every' becomes 'per' ('per' means 'for each' or 'for every').
'ta'+'per'='TAPER'
(Other definitions for taper that I've seen before include "Narrow gradually as candle may" , "Get to the point" , "Get more narrow" , "Thin progressively" , "Tail off; a spill" .)