As he arranged the cover up (7)
I believe the answer is:
sheathe
'cover up' is the definition.
'sheathe' can be an answer for 'cover' (to sheathe something is to cover it). I am not sure about the 'up' bit.
'as he arranged the' is the wordplay.
'arranged' is an anagram indicator.
'as'+'he'='ashe'
'ashe' with letters rearranged gives 'shea'.
'shea'+'the'='SHEATHE'
Can you help me to learn more?
(Other definitions for sheathe that I've seen before include "Put (a sword) into its holder" , "Cover in case" , "Put away (a sword)" , "stow away safely" , "Put (a sword) it its cover" .)