Support friend without breaking the law! (7)
I believe the answer is:
legally
'without breaking the law' is the definition.
(I've seen this before)
'support friend' is the wordplay.
'support' becomes 'leg' (leg is a kind of support).
'friend' becomes 'ally' (an ally is a friend or supporter).
'leg'+'ally'='LEGALLY'
(Other definitions for legally that I've seen before include "Lawfully" , "without breaking the law" , "according to the national regulations" , "In a manner approved by law" , "within the law" .)