Fellow leaves capital £1,000 pine (4)
I believe the answer is:
long
'pine' is the definition.
(to pine for something is to long for it)
I don't understand the remainder of the clue.
(Other definitions for long that I've seen before include "Protracted" , "Sustained" , "Extensive - pine" , "Thus having been treated by stretcher, perhaps" , "die" .)