A lot of extremely lamentable rubbish getting rejected (6)
I believe the answer is:
parcel
'a lot' is the definition.
(can mean a bunch or load of something)
'extremely lamentable rubbish getting rejected' is the wordplay.
'extremely' means to remove the middle letters.
'rubbish' becomes 'crap'.
'getting rejected' is a reversal indicator.
'lamentable' with its middle taken out is 'le'.
'le'+'crap'='lecrap'
'lecrap' in reverse letter order is 'PARCEL'.
'of' is the link.
(Other definitions for parcel that I've seen before include "'Bundle, package (6)'" , "Packet" , "One conveyed" , "Pack" , "Soft shade; crayon" .)