Silk cotton always gives a good finish (5)
I believe the answer is:
kapok
'silk cotton' is the definition.
(synonyms)
'always gives a good finish' is the wordplay.
I cannot quite understand how this works, but
'a' is within the answer.
'good' could be 'ok' and 'ok' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for kapok that I've seen before include "filler" , "A plant fibre used for stuffing and insulation" , "Silky vegetable fibre used as stuffing" , "Natural stuffing fibre" , "Stuffing for pillows" .)