A pitch, grey (4)
I believe the answer is:
ashy
'grey' is the definition.
(similar in meaning)
'a pitch' is the wordplay.
'pitch' becomes 'shy' (I've seen this before).
'a'+'shy'='ASHY'
(Other definitions for ashy that I've seen before include "pale greyish colour" , "evidence of recent fire" , "covered in dust" , "Like fireplace residue" , "Grey-coloured" .)