Professional farm vehicle that's used by geometry students (10)
I believe the answer is:
protractor
'professional farm vehicle that's used by geometry students' is the definition.
I can't judge whether this defines the answer.
'professional farm vehicle that's used by' is the wordplay.
'professional' becomes 'pro' (abbreviation).
'farm vehicle' becomes 'tractor' (I've seen this in another clue).
'that's used by' says to put letters next to each other.
'pro'+'tractor'='PROTRACTOR'
Can you help me to learn more?
(Other definitions for protractor that I've seen before include "Geometrical instrument" , "muscle" , "draughtsman may use this" , "Geometry set item" , "Angle-measuring device" .)