Fed up with close contest (6)

I believe the answer is:
defend
'contest' is the definition.
The answer and definition can be both to do with communicating as well as being verbs in their base form.
Maybe you can see an association between them that I can't see?
'fed up with close' is the wordplay.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'with' says to put letters next to each other.
'close' becomes 'end' (close can mean to end or finish).
'fed' written backwards gives 'def'.
'def'+'end'='DEFEND'
Can you help me to learn more?
(Other definitions for defend that I've seen before include "Protect, fight back" , "Protect against challenge or attack" , "Protect or assist against attack" , "Protect from harm" , "Protect - endorse" .)
