Sketch growing part of what's up for approval (9)
I believe the answer is:
thumbnail
'sketch' is the definition.
(I've seen this before)
'growing part of what's up for approval' is the wordplay.
I cannot really see how this works, but
'part' could be 'thumb' (thumb is a kind of part) and 'thumb' is located in the answer.
The remaining letters 'nail' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for thumbnail that I've seen before include "Digital process" , "small picture" , "Sort of sketch" , "Kind of sketch r" , "This sketch is short and concise like manual appendage" .)