Loosen and dig up segment of dogwood nuisance (4)
I believe the answer is:
undo
'loosen' is the definition.
(I know that loosen can be written as undo)
'up segment of dogwood nuisance' is the wordplay.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'segment of' indicates the answer is hidden within the clue (I've seen this in other clues).
'odnu' can be found hidden inside 'dogwood nuisance'.
'odnu' back-to-front is 'UNDO'.
'and dig' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for undo that I've seen before include "Untie, loosen" , "Cause to become loose" , "Loosen; annul" , "Ruin, destroy" , "Take apart" .)