Not cricket in the dark! (6)
I believe the answer is:
unfair
'dark' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I don't see?
'not cricket' is the wordplay.
'not' becomes 'un' (prefix meaning 'not').
'cricket' becomes 'fair' (I've seen this in another clue).
'un'+'fair'='UNFAIR'
'in the' is the link.
Can you help me to learn more?
(Other definitions for unfair that I've seen before include "Unjust, partial" , "Affected by partiality - dishonest" , "Not equitable - or blonde?" , "deceitful" , "Partisan" .)