Maintain it's a very short text (4)
I believe the answer is:
aver
'maintain' is the definition.
(averring is a kind of maintaining)
'a very short text' is the wordplay.
'very short text' becomes 'ver' (I can't explain this - if you can you should give a lot more credence to this answer).
'a'+'ver'='AVER'
'it's' is the link.
Can you help me to learn more?
(Other definitions for aver that I've seen before include "Profess" , "State firmly, perhaps rave" , "State firmly - even rave about" , "Prove to be true" , "To declare or affirm solemnly as true" .)