Poor thing? Regard staff guard? (5,8)
I believe the answer is:
night watchman
'guard?' is the definition.
(night-watchman is a kind of guard)
'poor thing? regard staff' is the wordplay.
'poor' indicates an anagram.
'regard staff' becomes 'watchman' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'thing' with letters rearranged gives 'night'.
'night'+'watchman'='NIGHT-WATCHMAN'
Can you help me to learn more?
(Other definitions for night watchman that I've seen before include "Astronomer" , "Security guard for the hours of darkness" , "making late arrival at Lord's?" , "Earlier than expected arrival at the batting crease?" , "Batsman sent in to play out time near the end of a day's play" .)