Plant agents to catch one up early (7)
I believe the answer is:
clarkia
'plant' is the definition.
(flowering plant)
'agents to catch one up early' is the wordplay.
'agents' becomes 'cia'.
'to catch' indicates putting letters inside.
'one up early' becomes 'lark' (as in being up with the lark, getting up early).
'cia' going around 'lark' is 'CLARKIA'.
(Other definitions for clarkia that I've seen before include "White, pink or purple-flowered plant" , "Showy garden plant; lack air (anagram)" , "Lack air (anag) - garden flower" .)