The poilu's hair dressing? (3)
I believe the answer is:
oil
'hair dressing?' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'the poilu's' is the wordplay.
'OIL' is hidden within the letters.
But, I am not sure how this is indicated.
Can you help me to learn more?
(Other definitions for oil that I've seen before include "Anoint" , "Grease" , "Black gold" , "painting" , "Viscous substance as lubricant" .)