Made up for being poorly prepared (6)
I believe the answer is:
offset
'made up for' is the definition.
The definition suggests a singular noun which matches the answer.
'poorly prepared' is the wordplay.
'poorly' becomes 'off' (I can't justify this - if you can you should believe this answer much more).
'prepared' becomes 'set' (I've seen this before).
'off'+'set'='OFFSET'
'being' acts as a link.
Can you help me to learn more?
(Other definitions for offset that I've seen before include "Counteract to compensate" , "Compensation; printing technique" , "Place out of line" , "make an effort" , "Compensate(d) for" .)