Longed for time to take up study? (7)
I believe the answer is:
'longed for' is the definition.
(I've seen this before)
'time to take up study' is the wordplay.
'time' becomes 'year' (I've seen this in other clues).
'to take up' says the letters should be written in reverse (I've seen 'taken up' mean this).
'study' becomes 'den' (term for a study or office).
'den' in reverse letter order is 'ned'.
(Other definitions for yearned that I've seen before include "Did long" , "Felt longing (for something)" , "Pined" , "Desired strongly and persistently" , "Longed (for something)" .)