Regretted putting a tree in the shade (7)
I believe the answer is:
repined
'regretted' is the definition.
(I've seen this before)
'a tree in the shade' is the wordplay.
'a tree' becomes 'pine' (pine is a kind of tree).
'in the' indicates putting letters inside.
'shade' becomes 'red' (red is a colour or shade).
'pine' inserted into 'red' is 'REPINED'.
'putting' is the link.
(Other definitions for repined that I've seen before include "Languished" , "Expressed discontent" , "Was not happy" , "Fretted; was discontented" , "Grudged" .)