Appealing to reduce vitamin (4)
I believe the answer is:
cute
'appealing' is the definition.
(I've seen this before)
'reduce vitamin' is the wordplay.
'reduce' becomes 'cut' (synonyms).
'vitamin' becomes 'E' (E is an example).
'cut'+'e'='CUTE'
'to' acts as a link.
(Other definitions for cute that I've seen before include "Pretty and attractive" , "Endearing" , "Location" , "Small and attractive - cunning" , "Quaintly pleasing" .)