Grow weary as car part is discussed aloud (4)
I believe the answer is:
tire
'grow weary' is the definition.
(synonyms)
'car part is discussed aloud' is the wordplay.
'car' becomes 't'.
'part' indicates taking the first letters.
'discussed aloud' becomes 're' (I am not sure about this - if you are sure you should believe this answer much more).
The initial letter of 'is' is 'i'.
't'+'i'+'re'='TIRE'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for tire that I've seen before include "Feel in need of rest" , "Flag" , "one of four found on Chevrolet?" , "Become weary" , "Grow weary of rite" .)