Tree some outlaw guards (6)
I believe the answer is:
banyan
'tree' is the definition.
(banyan tree is a kind of tree)
'some outlaw guards' is the wordplay.
'some' becomes 'any' ('any' can be similar in meaning to 'some').
'outlaw' becomes 'ban' (banning is a kind of outlawing).
'guards' is an insertion indicator.
'any' placed inside 'ban' is 'BANYAN'.
(Other definitions for banyan that I've seen before include "Multi-trunked Indian tree" , "one that does give a fig" , "plant" , "Any ban for an Indian tree" , "Fig-tree found in th bay, Nan." .)