Rubbish celebrity almost securing a great deal (7)
I believe the answer is:
flotsam
'rubbish' is the definition.
(flotsam is wreckage from a ship)
'celebrity almost securing a great deal' is the wordplay.
'celebrity' becomes 'fame' (celebrity can mean the quality of being famous).
'almost' means to remove the last letter (almost the whole word is kept).
'securing' indicates putting letters inside.
'a great deal' becomes 'lots' (I've seen this before).
'fame' with its final letter taken off is 'fam'.
'fam' going around 'lots' is 'FLOTSAM'.
(Other definitions for flotsam that I've seen before include "Things going adrift" , "Wreckage found floating" , "Goods lost" , "Vagrants" , "Rubbish on sea" .)