Longed for tree on the day (5)
I believe the answer is:
pined
'longed for' is the definition.
(I've seen this before)
'tree on the day' is the wordplay.
'tree' becomes 'pine' (pine is a kind of tree).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'the day' becomes 'd' (abbreviation for day).
'pine'+'d'='PINED'
(Other definitions for pined that I've seen before include "Longed; wasted (away)" , "Starved" , "Became ill with longing" , "Languished, yearned" .)