Intended poor end to act (5)
I believe the answer is:
meant
'intended' is the definition.
(to mean something is to intend it)
'poor end to act' is the wordplay.
'poor' becomes 'mean' (similar in meaning).
'end to' says to take the final letters.
The final letter of 'act' is 't'.
'mean'+'t'='MEANT'
(Other definitions for meant that I've seen before include "designed" , "Had as intention or purpose" , "planned" , "Signified" , "Had as purpose or design" .)