Grey adult initially reluctant to come forward (4)
I believe the answer is:
ashy
'grey' is the definition.
(similar in meaning)
'adult initially reluctant to come forward' is the wordplay.
I cannot really see how this works, but
'adult' could be 'a' (abbreviation) and 'a' is located in the answer.
'reluctant' could be 'shy' (I've seen this in other clues) and 'shy' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ashy that I've seen before include "Like burnt remains" , "resembling cinder track?" , "Like, eg, volcanic dust" , "pale greyish colour" , "Like burnt residue" .)