It's growing dapper (6)

I believe the answer is:
spruce
'dapper' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for spruce that I've seen before include "Smart, trim" , "perfect condition" , "Tidy - fir" , "wood" , "One [TYPE OF TREE]" .)