Disprove claim that umpire needs a work car (6)
I believe the answer is:
refute
'disprove claim' is the definition.
'refute' can be an answer for 'disprove' (refuting is a kind of disproving). I am unsure of the 'claim' bit.
'umpire needs a work car' is the wordplay.
'umpire' becomes 'ref' (short for referee).
'needs' means one lot of letters go next to another.
'a work car' becomes 'ute' (I am not sure about this - if you are sure you should believe this answer much more).
'ref'+'ute'='REFUTE'
'that' acts as a link.
Can you help me to learn more?
(Other definitions for refute that I've seen before include "Negate" , "Disprove" , "Prove to be incorrect" , "Prove that statement or accusation is wrong" , "Rebut; deny" .)