End period in a half-erected tent (9)
I believe the answer is:
terminate
'end' is the definition.
(synonyms)
'period in a half-erected tent' is the wordplay.
'period' becomes 'term' (term is a kind of period).
'a half' indicates taking half.
'erected tent' becomes 'nate' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' with half the letters taken is 'i'.
'term'+'i'+'nate'='TERMINATE'
Can you help me to learn more?
(Other definitions for terminate that I've seen before include "Put an end to, discontinue" , "Stop" , "Close" , "Conclude" , "Bring to an end" .)