Give sharp edge to sweet stuff mostly (4)
I believe the answer is:
hone
'give sharp edge' is the definition.
'sweet stuff mostly' is the wordplay.
'sweet stuff' becomes 'honey' (I've seen this before).
'mostly' means to remove the last letter.
'honey' with its final letter removed is 'HONE'.
'to' is the link.
(Other definitions for hone that I've seen before include "Smooth stone" , "Sharpen tool on stone" , "Sharpen (a blade)" , "Polish" , "Strop" .)