Rubbish in lean period halved, a good deal being kept (7)
I believe the answer is:
flotsam
'rubbish' is the definition.
(flotsam is wreckage from a ship)
'lean period halved a good deal being kept' is the wordplay.
'lean period' becomes 'famine' (period of great hunger).
'halved' indicates taking half.
'a good deal' becomes 'lots' (I've seen this in another clue).
'being kept' means one lot of letters goes inside another.
'famine' cut in half is 'fam'.
'fam' placed around 'lots' is 'FLOTSAM'.
'in' is the link.
(Other definitions for flotsam that I've seen before include "Vagrants" , "Things going adrift" , "Washed-up wreckage" , "The floating wreckage of a ship" , "Detritus" .)