Give protection though fed up before the finish (6)
I believe the answer is:
defend
'give protection though' is the definition.
I can't tell whether this definition defines the answer.
'fed up before the finish' is the wordplay.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'before' is a charade indicator (letters next to each other).
'the finish' becomes 'end' (I've seen this in other clues).
'fed' backwards is 'def'.
'def'+'end'='DEFEND'
Can you help me to learn more?
(Other definitions for defend that I've seen before include "Compete to retain (sporting title)" , "Block, as in cricket" , "Protect, fight back" , "Fortify" , "Champion" .)