Erratic taxi rage comes freely (2,6)
I believe the answer is:
ex gratia
'comes freely' is the definition.
I can't tell whether this defines the answer.
'erratic taxi rage' is the wordplay.
'erratic' indicates anagramming the letters.
'taxi'+'rage'='taxirage'
'taxirage' anagrammed gives 'EX GRATIA'.
Can you help me to learn more?
(Other definitions for ex gratia that I've seen before include "This payment is not a legal obligation" , "As a favour, not compelled by legal right" , "Given without payment" , "Given as concession without legal compulsion" , "(Of payment) given as a favour but not required" .)