Dishonest remark about indigestible material (5)
I believe the answer is:
fibre
'indigestible material' is the definition.
'fibre' can be an answer for 'material' (fibre is a kind of material). I am unsure of the 'indigestible' bit.
'dishonest remark about' is the wordplay.
'dishonest remark' becomes 'fib' (I can't explain this - if you can you should give a lot more credence to this answer).
'about' becomes 're' ('re' means regarding or about).
'fib'+'re'='FIBRE'
Can you help me to learn more?
(Other definitions for fibre that I've seen before include "Brief (anag.)" , "Textile thread; roughage" , "Thread, strand" , "Long fine thread" , "Thread, filament" .)