When there's a house to do up, you need cover (4)
I believe the answer is:
hood
'cover' is the definition.
(I know that hood is a type of cover)
'when there's a house to do up' is the wordplay.
'when' becomes 'o' (I can't explain this - if you can you should believe this answer much more).
'there's a house' becomes 'h'.
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'o'+'h'='oh'
'oh' put after 'do' is 'dooh'.
'dooh' reversed gives 'HOOD'.
'you need' is the link.
Can you help me to learn more?
(Other definitions for hood that I've seen before include "academic garment" , "A cover; Bismarck sank it, 1941" , "Cover < the upper part < of tough" , "this could provide cover" , "See 5" .)