Scaling insect's back on duck fluff (4)

I believe the answer is:

lint

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'duck fluff' is the definition.
'lint' can be an answer for 'fluff' (thesaurus). I am unsure of the 'duck' bit.

'scaling insect's back on' is the wordplay.
'scaling' becomes 'lin' (I can't justify this - if you can you should believe this answer much more).
'back' says to take the final letters.
'on' means one lot of letters go next to another.
The final letter of 'insect' is 't'.
'lin'+'t'='LINT'

Can you help me to learn more?

(Other definitions for lint that I've seen before include "Wound-dressing fabric" , "Wound dressing" , "Absorbent material for dressing wounds" , "Fabric for dressing wounds" , "Soft cloth for dressing wounds" .)

I've seen this clue in the Sydney Morning Herald.

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