Paul worked with Troy on boat propeller (8)
I believe the answer is:
catapult
'propeller' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'paul worked with troy on boat' is the wordplay.
'worked with' indicates anagramming the letters.
'troy' becomes 't' (abbreviation - troy is a unit of weight).
'on' indicates putting letters inside.
'boat' becomes 'cat' (short for catboat).
'paul' with its letters mixed up with 't' can make 'tapul'.
'tapul' inserted within 'cat' is 'CATAPULT'.
Can you help me to learn more?
(Other definitions for catapult that I've seen before include "Y-shaped weapon associated with naughty boys" , "Simple elastic device for shooting projectiles" , "Device for firing stones or rocks" , "Forked-stick launcher" , "Stone-thrower" .)