Energetic girl repressing anger left (8)
I believe the answer is:
tireless
'energetic' is the definition.
(similar in meaning)
'girl repressing anger left' is the wordplay.
'girl' becomes 'tess' ().
'repressing' means one lot of letters goes inside another.
'anger' becomes 'ire' (ire is intense rage).
'left' becomes 'L' (common abbreviation).
'ire'+'l'='irel'
'tess' placed around 'irel' is 'TIRELESS'.
(Other definitions for tireless that I've seen before include "Having great energy" , "Full of energy" , "Never grows weary, inexhaustible" , "Full of stamina" , "Having inexhaustible energy" .)