Such an excuse is out of place (5)
I believe the answer is:
alibi
This clue might be a double definition.
'such an excuse' is the first definition.
'alibi' can be an answer for 'excuse' (excuse given by a suspect in an investigation). I'm unsure of the 'such an' bit.
'out of place' is the second definition.
'alibi' can be an answer for 'out' (I've seen this in another clue). I am unsure of the 'of place' bit.
'is' is the link.
Can you help me to learn more?
(Other definitions for alibi that I've seen before include "A claim one was elsewhere when crime took place" , "Excuse, defence" , "It shows one wasn't at crime scene" , "Story confirming innocence" , "Timely plea?" .)