Shortly to be covered in sketches and so forth (8)
I believe the answer is:
etcetera
'and so forth' is the definition.
(synonyms)
'shortly to be covered in sketches' is the wordplay.
'shortly' means to remove the first letter.
'to be' becomes 'vet' (vetting is a kind of being).
'covered in sketches' becomes 'cetera' (I can't explain this - if you can you should give a lot more credence to this answer).
'vet' with its initial letter taken away is 'et'.
'et'+'cetera'='ETCETERA'
Can you help me to learn more?
(Other definitions for etcetera that I've seen before include "And the rest" , "and the like" .)