Mostly short and thick, giving tip (4)
I believe the answer is:
dump
'tip' is the definition.
(thesaurus)
'mostly short and thick' is the wordplay.
'mostly' means to remove the last letter.
'short and thick' becomes 'dumpy' (I've seen this before).
'dumpy' with its last letter taken off is 'DUMP'.
'giving' is the link.
(Other definitions for dump that I've seen before include "Site for rubbish" , "Dispose of" , "Empty out" , "Heap of rubbish" , "Jilt" .)