Marry poet, sadly short-term (9)
I believe the answer is:
temporary
'short-term' is the definition.
(I've seen this before)
'marry poet sadly' is the wordplay.
'sadly' indicates anagramming the letters.
'marry'+'poet'='marrypoet'
'marrypoet' anagrammed gives 'TEMPORARY'.
(Other definitions for temporary that I've seen before include "short-term" , "here today, gone tomorrow" , "not for good" , "Lasting for a limited period" , "Not for long" .)