All right, if it's not too dark (4,6)
I believe the answer is:
fair enough
'too dark' is the definition.
I know nothing about this answer so I can't tell whether this works.
'all right if it's not' is the wordplay.
I cannot quite see how this works, but
'right' could be 'r' (common abbreviation) and 'r' is located in the answer.
'not' could be 'no' (negative) and 'no' is located in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for fair enough that I've seen before include "understandable" , "Very well" , "OK?" .)