One adept at serving (4)
I believe the answer is:
acer
'one adept at serving' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for acer that I've seen before include "Type of maple" , "Tree with winged fruit" , "Care about the maple?" , "Tree or shrub of the maple genus" , "ornamental tree" .)