Try to stop listener describing victory over United (9)
I believe the answer is:
endeavour
'try' is the definition.
(endeavouring is a kind of trying)
'stop listener describing victory over united' is the wordplay.
I cannot quite understand how this works, but
'stop' could be 'end' (synonyms) and 'end' is located in the answer.
'victory' could be 'v' and 'v' is found in the answer.
'over' could be 'o' (cricket abbreviation) and 'o' is found in the answer.
'united' could be 'u' and 'u' is located in the answer.
'listener' could be 'ear' (body part which hears or listens) and 'ear' is found in the remaining letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'to' is the link.
(Other definitions for endeavour that I've seen before include "Make a serious effort" , "Captain Cook's first ship - DCI Morse's first name" , "Undertaking" , "First space shuttle to visit the International Space Station" , "Aim" .)