American agents about to be hiding in tree? (6)
I believe the answer is:
acacia
'tree?' is the definition.
(acacia is a kind of tree)
'american agents about to be hiding in' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'agents' becomes 'cia'.
'about to' becomes 'ca' (I've seen this in other clues).
'be hiding in' indicates putting letters inside.
'a'+'cia'='acia'
'acia' enclosing 'ca' is 'ACACIA'.
(Other definitions for acacia that I've seen before include "Thorny shrub with yellow or white-flowers" , "Tree or shrub with yellow or white flowers" , "Spiny shrub with clusters of yellow or white flowers" , "Subtropical shrub or tree" , "Plant of the mimosa family" .)