Right through, struggle against the fear (6)
I believe the answer is:
'the fear' is the definition.
'right through struggle against' is the wordplay.
'right' becomes 'r' (abbreviation).
'through' means one lot of letters goes inside another (inserted letters go through the word).
'struggle against' becomes 'fight' (synonyms).
'r' going within 'fight' is 'FRIGHT'.
(Other definitions for fright that I've seen before include "Sudden exposure to fear" , "Panic" , "Sudden feeling of fear" , "Terror" , "Horror" .)